could possibly be called by this name are two broad, shallow pouches at the posterior end of the peribranchial sacs, one for each side. have nothing whatever to do with the budding, since the buds arise about as They certainly far away from them as the size of the ascidiozooids will permit. Furthermore, they do not have the same relations as the epicardium of Clavelina and other ascidians. In Goodsiria and Botryllus, I may add, they are merely parts of the peribranchial sacs; while in other cases they arise in a definite way from the branchial sac. In my opinion it is an unjustifiable and purposeless forcing of things to attempt to see anything in either Goodsiria or Botryllus that is homologous with the epicardium of Clavelina and other budding ascidians. Relying chiefly on the evidence from adult structure, we are, then, as it seems to me, obliged to conclude that the compound ascidians have arisen from the simple ones by at least two distinct groups of these latter having independently acquired the property of reproduction by budding. Now, since the processes of evolution are of quite as much scientific interest to us as are its products, we can hardly avoid an attempt to gain some insight into the developmental processes that have been in operation in this instance. One question we are impelled to ask is whether some cause for the origin of budding in these animals may not be detected here, where it, whatever it is, has been so potent as to produce its effect twice. A possible cause does suggest itself, and I venture to present it to you very briefly. I confess, however, that the venture is made not without some trepidation. It will be remembered that we have given reasons for regarding Goodsiria and Perophora as simplified or pigmy Polycarpa and Ascidiae respectively. It seems to me possible that budding might have arisen in these genera of simple ascidians as a result of the diminution in size and simplification in structure of some of the species; and I am disposed to regard the diminution in size as the most important factor. It appears to me that the smallest species of Polycarpa, for example, have a much poorer chance of survival than do the larger and largest ones, owing to the simple circumstance that they cannot produce anything like so large a number of embryos as do the larger species. The smallest species that I know of this genus is only 3 or 4 millimetres in length, while most of the species reach some centimetres at least in length; and it is a matter of common observation that in the ascidians the size of the ovary and the number of the ova are in direct proportion to the size of the parent individuals. It is certain that the total volume of the sexual products of a large Polycarpa would be many times greater than the entire animal of the small species to which I have just referred; and the ova in the one case are not much, if at all, larger in the one than in the other. The suggestion is that in these cases budding has in some way arisen as a compensation for the diminished power of sexual reproduction. A developmental question of wider moment than the one just disposed of, and one which I discuss with much greater confidence, is this. If blastogenesis has had two or more wholly independent origins among ascidians, how is the close similarity in the development of the blastozooids of the whole group to be explained? The interest of this question is greatly increased by the fact that not only is the development of the blastozooids much alike in all the species, but also that this development is quite unique as compared with the development of the embryozooid. In contrasting the development from an embryo and from a bud it is seen that in embryonic development the ectoderm produces the matrix of the test, the peribranchial sacs, and the central nervous system and hypophysial duct, while in the bud we see these four parts of the animal produced by the inner or so-called endodermic vesicle. Concerning the endodermic, or rather inner vesicle origin of the ganglion and hypophysial duct, I speak with perfect confidence as regards Goodsiria and Perophora, for this confidence rests on my own observations. The case for the Goodsiria bud in particular is as clear as anyone could wish a developmental fact to be. Enough of the facts are now before us to enable us to state the problem clearly. If the property of budding has been independently acquired by two quite widely separated groups of simple ascidians, how has it come about that the development of the blastozooids agrees so closely, and in such remarkable peculiarities, as the origin of the nervous system, and the peribranchial sac from the outer layer of the embryo and from the inner layer of the bud? I believe the answer to be that we have before us an excellent case of developmental opportunism. The inner layer of the bud gives origin to nearly all the organs of the blastozooid because physiological influences working to such a course of development have been stronger than the hereditary influences tending to make the development follow the embryonic method. The case is particularly interesting because, as I believe, we are able to put our finger on the physiological cause that has been so potent in modifying the direction, not the final result of the mighty force of heredity. You will remember that the outer layer of the embryo produces the matrix of the test, the nervous system, and the peribranchial sacs. Now observe. The production of the two last-mentioned structures is a purely developmental matter. It concerns the embryonic period only. The organs become separated, or practically so, from their source during this period, and the outer layer has nothing more to do with them, at least functionally. Not so with the production of the test. This is not merely an embryonic matter; it is an enduring physiological matter. The test must be constantly renewed throughout the life of the individual. The outer layer is consequently an active secretory organ from an early embryonal period to the end of the animal's life; and since the outer layer of the bud is merely a portion of the outer layer of the parent or of the stolon, as the case may be, it is at no time an embryonic layer; it is, from the very beginning, a differentiated organ. It has to grow, to be sure; but in addition it has a wellestablished and important physiological function to perform. Very different is it with the inner layer. Its cells are strictly undifferentiated-embryonic, if you will. They do not even have to digest their own food, for they are constantly bathed in the maternal blood. The layer does not come in contact with the external world at any time or at any point. It has nothing to do but to develop. Why should it not relieve the outer layer from producing some of the parts that it produces in the embryo? And it does. I must hasten to say that this physiological explanation of the peculiarities of ascidian bud development was suggested by Seeliger, though he did not make as much of it as I believe it deserves. There are several other instances among budding animals where I am inclined to think that assignable functional influences have more or less radically changed the method of development, but time prevents reference to more than one of these. Chun has very recently shown that in Rathkea octopunctata, one of the Medusæ, the inner layer of the parent takes no part whatever in the formation of the bud. The buds are produced on the wall of the stomach, and it appears to me highly probable that the ectoderm alone shares in the process, because the endoderm is so completely given over to the digestive function, while the ectoderm cells have much more largely retained their undifferentiated condition owing to their being in great measure protected from the external world by the subumbrella. 11. Outlines of a new Classification of the Tunicata. By WALTER GARSTANG, M.A., F.Z.S., Fellow of Lincoln College, Oxford. Professor Herdman's classification of the Tunicata is based very largely upon modifications of external form connected with gemmation and the formation of colonies. It involves, as Professor Herdman himself admits, an unnatural separation of forms admittedly allied, e.g., Pyrosoma and Doliolum, Clavelina and the Distomidae, Diazona and Ciona, as well as to an unnatural approximation of forms whose structure is altogether dissimilar, e.g., Pyrosoma and Cœlocormus, Perophora and Clavelina. Lahille has promulgated a system based upon modifications of the structure of the pharynx. His arrangement of the fixed ascidians seems to me admirable, but his treatment of the pelagic forms is most unsatisfactory. He follows Herdman in placing Pyrosoma near Calocormus and the Didemnidæ, though upon different and purely speculative grounds. Salpa is divorced from Doliolum through an erroneous interpretation of the ciliated pits on the gill of Salpa. The subjoined scheme is based upon anatomical and embryological facts. The pelagic caducichordate types possess a single row of undivided branchial slits (protostigmata). This condition is recapitulated, as I have elsewhere shown, in the ontogeny of various fixed ascidians, but the protostigmata of the young postlarval form are subsequently subdivided into rows of minute secondary stigmata. The structure of Pyrosoma and its allies is thus more primitive than that of any of the fixed ascidians. The two groups, Thaliacea and Ascidiacea, are distinguished in my scheme upon this basis. My subdivision of the Thaliacea explains itself; that of the Ascidiacea I have adopted, with some modifications, from Labille. PERENNICHORDATA. TUNICATA. I. Endostylophora.-Pharynx provided with an endostyle. E.g., Oikopleura, Fritillaria. II. Polystylophora. Endostyle absent; pharynx provided with numerous finger-like processes arranged in rows. E.g., Kowalevskia. CADUCICHORDATA. I. Thaliacea.-Protostigmata undivided; cloaca posterior. Pelagic. II. Ascidiacea. - Protostigmata subdivided into rows of secondary stigmata; Fixed. i. Stolidobranchia.-Pharynx with internal longitudinal bars; bars solid and ribbon-shaped. E.g., Botryllus, Cynthia, Goodsirea. ii. Phlebobranchia.-Pharynx with internal longitudinal bars; bars tubular and vascular. E.g., Perophora, Ascidia, Diazona. iii. Aplousobranchia.-Pharynx without internal longitudinal bars; horizontal membranes present. E.g., Clavelina, Distaplia, Amaræcium, Didemnum. 12. On the Presence of Skeletal Elements between the Mandibular and Hyoid Arches of Hexacanthus and Læmargus. By Dr. PHILIP WHITE. 13. On the Presence of a Sternum in Hexanchus griseus. 14. On the Creodonta. By Professor W. B. Scott. Our knowledge of this remarkable group of extinct flesh eaters has been of slow growth, and only lately has sufficiently perfect material been recovered to give us an accurate insight into the structure and relationships of several of the more important genera. The creodonts are almost exclusively Eocene forms, and especially characterise the Lower Eocene, the Wasatch being probably their time of culmination, while only one genus (Hyænodon) is known to pass into the Miocene. The appearance of five distinctly differentiated families in the Puerco indicates that their origin is to be looked for in the Cretaceous formation. North America was eminently the home of the group, having many more genera and families than Europe has yet yielded. So far, none are known from the southern hemisphere. Though including several divergent lines of differentiation, the group is characterised by a fairly uniform structure. The incisors and canines are of the carnivorous type, and rarely are reduced in number; the sectorials are either absent or present in more than one pair (except in the Miacida); the molars generally retain the tritubercular plan more or less distinctly. The milk dentition is of the same character as in the true carnivora. The brain is small and the hemispheres usually little convoluted. The skull has a very long slender cranial part, with deep postorbital constriction, very prominent sagittal and occipital crests, and a short facial region. The vertebræ are remarkable for the complex zygapophyses on the lumbars and posterior thoracics. The limbs are relatively short and light, the humerus retaining the epicondylar foramen, and the femur the third trochanter. The feet are weak and almost invariably plantigrade and pentadactyl, and with only one known exception, the scaphoid, lunar, and central remain separate. The ungual phalanges are very generally cleft at the tip, as in the insectivora. The creodonts fall quite naturally into two sections, one with more or less blunt and tuberculated teeth, and the other with trenchant teeth. The first section, which includes three families, the Arctocyonidæ, Triisodontidæ and Mesonychidæ, is most abundant in the Puerco, and has but a single representative in the Middle and Upper Eocene. No existing forms appear to have been derived from the creodonts with tuberculate teeth. The second section includes five families, the Proviverridæ, Oxyænidæ, Hyænodontidæ, Palæonictidæ, and Miacidæ, the last of which is very sharply distinguished from all other creodonts, and forms the connecting link with the true carnivora. The creodonts with trenchant teeth are most important and highly developed in the Wasatch and Bridger, after which they decline, their place being gradually taken by the carnivores. Most of the fissipede carnivora would seem to be clearly derivable from the Miacida, except the cats, the origin of which is still obscure, and which are remarkable for the extremely rapid specialisation which they attain at a very early period. The Pinnipedia, on the other hand, would seem to have been derived from some other creodont family. Wortman has suggested, with considerable probability, that the Oryenida were the ancestors of the Pinnipedes, but the gap between the two is yet so great as to render this uncertain. 1. On some Results of Scientific Investigation as applied to Fisheries. By Professor W. C. M'INTOSH, F.R.S. My remarks are based on experience mainly, but not altogether, gained in Scotland, but are applicable to the empire, or indeed to European fisheries. The greater responsibility has been felt, since England possesses no public department precisely corresponding to the Fishery Board for Scotland. It may be pointed out that such investigations in regard to the fisheries are of so recent a date that perhaps it is too early to estimate comprehensively the results; but since there are hostile critics it may be well to take a general survey of the results-often gained under considerable difficulty, especially in regard to sea-going ships, for only a small steam vessel has been at the service of the Fishery Board, instead of a powerful vessel capable of going to distant grounds in rough weather. Previous to 1883 no statistics of a reliable kind, other than those of herrings and salted fishes, were available to guide the Legislature as to whether marine fisheries were diminishing, stationary, or increasing. This anomalous state of things permitted indulgence in exaggerated statements as to the scarcity of fishes, and the decline, or, as it was said, impending ruin of the fisheries. While thus a very great improvement had been made, the returns were far from being complete. They give the greater part of the fishes caught, but left many unreported. If anything is national property it is the sea, and it ought to be comparatively an easy task to give an account of its stewardship. In the scientific report to the Royal Commission of 1884 the closing of certain bays against beam and otter trawling was indicated thus:-The experiment of allowing a bay having a definite boundary and suitable for observation to remain unfished for several years either by line, trawl, or stake-net would perhaps be more satisfactory' (than a close time). Its fish fauna would be carefully examined at closure, and frequently during the period, and the general increase in size, emigration, and immigration of the fishes noted. Advantage might be taken at the same time to increase the number of its valuable food-fishes, e.g., turbot and soles, by artificial means. Such an experiment would give a valuable basis for future legislation, tend to increase our knowledge of the food-fishes in a remarkable degree, and would be worthy of the interests which this country has in the department of sea fisheries.' It was afterwards arranged to leave out the line fishermen, since many of the older men with small boats would have suffered hardship; and, after some years' observations, the Fishery Board decided to close all the water within the three-mile limit, besides certain larger areas. These closures were made, rightly or wrongly, on the faith of the scientific experiments made by the Board. The investigations also showed from 1884 onwards that the three-mile limit was insufficient to protect the spawning fishes, which, as a rule, were beyond that area. Investigation has also cleared up the migrations of fishes. In shallow bays ripe plaice are seldom found, almost all occurring in the deeper water beyond the three-mile limit. Yet the number of young plaice in such areas is prodigious, the eggs and young being wafted into the shallower water. There they grow till they reach a size of 10 to 13 inches, when they seek the outer waters, in which to attain maturity and to grow to full size. This explains the occurrence of the enormous number of these fishes in so limited an area, as, for instance, in St. Andrews Bay, and their survival after the use of the most extensive and persistent means of capture. Similarly, while the cod spawns are in the off-shore waters, the very young forms, ranging from in. to an inch, appear in the in-shore grounds in June, haunt the borders of the tidal rocks for some time, and again return to breed in deep water. On the other hand, the very young haddock is an off-shore fish; and so is the very young ling, the latter, when from three to seven inches, migrating shorewards and returning to deep water for adult life. Scientific investigation has shown the enormous fecundity of foodfishes, as well as the provision by which only a portion of the roe ripens at a given time. With wise regulations, therefore, our waters might always be relied on for supplies. We have largely increased our knowledge of the sizes of the respective sexes of marine fishes at maturity, and the development of the eggs in the roe, and their numerical proportion to each other. In this work no one had done more valuable service than Dr. Fulton, the Scientific Superintendent of the Fishery Board for Scotland, and the subject has been further elucidated by Mr. J. T. Cunningham, Mr. Calderwood, and Mr. Holt. Such knowledge in regard to Scotland made it clear that the legislative proposal of a size-limit of 10 or 12 inches-below which fishes were to be unsaleable-would be no protection, for instance, to a ripe plaice, though it might tend to preserve the species till it reached somewhat deeper waters. No feature, again, has been more prominently brought out by scientific investigation than the fact that the eggs of almost all our food-fishes float, or are pelagic. Their wide distribution is thus provided for, and they are beyond the possibility of injury by net or trawl. In 1884 both the eggs and the young of foodfishes were, as a rule, wrapt in mystery. Now the eggs and larval stages of most have been described and figured, notably by Professor E. Prince, Mr. Cunningham, 1895. 3 A |