Char. Body flattened; the mouth ventral, subcentral, encircled with a broad annular sphincter: eyes two, approximate, on the dorsum behind the apex and anterior to the mouth. Lacustrine. The ova capsulated. 1. M. rostratum, elongate, elliptical, acuminate, and alike at both ends, whitish and pellucid or tainted a yellowish-red; eyes reddish, approximate; mouth central; egg-capsules dark brown. Length 3""; breadth 1"". Fasciola rostrata, Müll. Verm. i. ii. 65. Planaria rostrata, Müll. Zool. Dan. Prod. 222; Zool. Dan. iii. 40. tab. 105. f. 6. Turt. Gmel. iv. 65. Planaria velox, Dalyell, Planar. 127. f. 17. Derostoma rostratum, Dugés in Ann. des Sc. nat. xxi. 79. pl. 2. f. 16. Hab. Ponds. 9. OPISTOMUM, Schmidt. Opistomum, Diesing, Syst. Helm. i. 233. Schultze, Naturg. der Char. Body flattish, with an anterior subterminal mouth; the œsophagus pitcher-shaped, not protrusile: eyes none. Lacustrine. 1. Op. serpentina, tongue-shaped, dilated and rounded in front, lanceolate behind, white or grey. Length 2"". Planaria serpentina, Dalyell, Pow. Creat. ii. 122. pl. 15. f. 20, 21. Hab. Pools of fresh water. Desc. "Length between one and two lines; body flattened; head obtuse, enlarging towards each side, and somewhat depressed in the centre of the front, where there seems a circular orifice, probably the mouth. The interranea, occupying much of the body, of a dark colour, and resembling curving or circular sacs. Colour of the animal white, or grey under the microscope. Motion smooth and gliding as that of other Planariæ. No eyes visible."-Dalyell. 10. TYPHLOPLANA, Ehrenberg, 1831. Typhloplana, Oersted, Entw. Plattw. 71. Dies. Syst. Helm. i. 231. Char. Body linear-oblong, planaroid, the oral aperture ventral, near the middle or posterior to the middle of the body: eyes none. 1. T. fœcunda, nearly linear or a little swollen at the middle with obtusely rounded extremities, white. Length "". Planaria stagni, Dalyell, Pow. Creat. ii. 118. pl. 16. f. 30. Hab. Ponds in autumn. Obs. The very slight difference on which Dalyell has founded the distinction of his species, depends, undoubtedly, on the more or less developed state of the ova. There are twelve or fourteen of these in some individuals, which occupy nearly the whole body. 2. T. prasina, obtuse in front, tapering to a point behind, grassgreen. Length "". Planaria prasina, Dalyell, Pow. Creat. ii. 121. pl. 15. f. 15. Hab. Ponds in autumn: gregarious. Desc. "Length of the largest about half a line; thickness about the fifth of the length. Body roundish; head obtuse; tail tapering to a point. Colour beautifully grass-green. Motion active."- "One or two brown ova seemed to be in one or two specimens."-Dalyell. 3. T. flustræ, body convex above, flattened below, linear-elongate, rounded and equal at both ends, white, with a dark spot on the neck. Length 2""; breadth "". Planaria flustræ, Dalyell, Pow. Creat. ii. 118. pl. 16. f. 32. Hab. "Dwells on the Flustra hispida, where it is not rare in July and August."-Dalyell. Obs. "Motion very swift. Apparently sustained by an invisible thread when falling through the water."-Dalyell. 11. CONVOLUTA. Convoluta, Oersted, Entw. Plattw. 75 (1844). Diesing, Syst. Helm. i. 218. Schmidt, Neue Rhabdocal. 5. Char. Body flat, obtuse in front and narrowed backwards, with the margin longitudinally involute: mouth minute, ventral, anterior: Marine. eyes none. 1. C. paradoxa. Planaria convoluta, Abildgaard in Müll. Zool. Dan. iv. 26. tab. 142. Convoluta paradoxa, Oersted, Entw. Plattw. 75. f. 33, 35, 36. Dies. Convoluta Johnstoni, Dies. Syst. Helm. i. 219. Planaria haustrum, Dalyell, Pow. Creat. ii. 106. pl. 14. f. 36, 37. Hab. Amongst confervæ between tide-marks. Desc. Body 2"", brown, oblong, truncate in front and paler coloured, narrowed posteriorly. The anterior extremity, in some positions, is marked with a pale subcircular spot (the mouth), while, in others, a light-coloured line runs down the centre, and the margins are folded so as to form almost a tube. There are two ventral pores, of which the anterior is oral, and the posterior genital. Very active. The following are doubtful species of this family : Planaria cuneus, wedge-shaped, the front widest and truncate, greyish-brown. Length "". Planaria cuneus, Dalyell, Pow. Creat. ii. 121. pl. 15. f. 16, 17. Hab. Blackhall Pond, Dalyell. Desc. "Head obtuse, the corners rounded as it advances, and the portion between them depressed. Body thick, flattened; tail acute. Colour greyish-brown. No eyes visible."-Dalyell. In the figure, however, a single eye in front, midway between its angles, is distinctly shown. The species is very like the Planaria truncata of Müller, which has four eyes. Oersted considers the latter to be synonymous with his Vortex littoralis, which he describes and figures with two eyes (Entw. Plattw. 64). See also Dies. Syst. Helm. i. 229. Planoides fusca. Planoides fusca, Dalyell, Pow. Creat. ii. 123. pl. 16. f. 35, 36. Hab. The sea-shore. Desc. "Length a line and a half; breadth and thickness nearly half the length. Body compact, solid; the anterior extremity divided horizontally into two lips, wherein is perhaps the mouth. This extremity is fashioned somewhat as a scoop by the fold of a membranaceous edge, apparently reflected on the back. A dark red internal organ is situate towards the centre of the body. Neither eyes nor marginal specks have been discovered, nor any prominent parts of external organization. Colour brownish, speckled. Motion smooth and gliding."-Dalyell. Planaria hirudo, body linear, lengthened, brown, marked in front with a black point and line; two pale spots above the circular tail. Length 4"". Planaria hirudo, Johnston in Ann. & Mag. Nat. Hist. xvi. 437. pl. 15. f. 3. Dies. Syst. Helm. i. 473. Hab. The littoral region amongst confervæ. Desc. The body is of a uniform light brown colour excepting the two pale spots near the tail, and, when fully stretched, is of a narrow linear figure, slightly tapered in front. There is a small black dot about half a line behind the anterior end, and a dark line runs from it forward to the tip. These are not formed by an eye, or a cluster of eyes, but the line seems rather to be produced by some internal tube, and the dot by some harder, perhaps horny, substance. Very active. Motion continuous.-Seems to be nearly related to the Pla C naria longiceps of Dugès (Ann. des Sc. Nat. xxi. 83 (1830), pl. 2. f. 21; Dies. Syst. Helm. i. 207). "Prostoma? armatum?, translucent and gelatinous, with the cephalic points orange, and scattered irregularly. Prostoma armatum, Templeton in Loud. Mag. Nat. Hist. ix. 236. f. 29 a. Johnston in Ann. & Mag. Nat. Hist. xvi. 436. Hab. "Found among Conferva spiralis from a drain in the bog meadows," near Belfast.-Templeton. Obs. The anterior end is rounded and almost orbicular; the posterior oblong and obtuse. The eyes extend a good way down the body, which appears to be about 2 inches long; but it is probably represented considerably magnified. The species has no resemblance to the Prostoma armatum of Dugès; but it seems to be a member of the genus as now restricted. Cercaria. Cercaria, Dalyell, Pow. Creat. ii. 266. pl. 36. f. 9. Hab. Fresh water. Desc. "This is a minute animalculum, somewhat resembling a Planaria, with an annulated tapering tail. The mouth is an orifice in the centre of the anterior extremity. The body is of mutable form, the tail very extensile, when the rings are almost obliterated. Colonies of these animals, like white specks, dwell in fresh water.". Dalyell. II. TERETULARIA. TERETULARIA, Blainville in Dict. des Sc. nat. lvii. 573 (1828). CESTOIDINA, Oersted, Entw. Plattw. 76 (1844). Ray Soc. Rep. NEMERTINA, Oersted, Entw. Plattw. 80. LININE, Johnston in Ann. & Mag. Nat. Hist. xvi. 434 (1846). NEMERTEA, De Quatrefages, Voy. en Sicile, ii. 95. NEMERTINES, E. Blanchard in Ann. des Sc. nat. viii. 123 (1847). Obs. In the present state of our knowledge of this suborder it cannot be advantageously divided into families. The structure of many species has been demonstrated, but anatomists differ widely as to the function of the organs described; and hence I have avoided their nomenclature, lest error should be thus continued. It may be considered as proved that the mouth is terminal; and, in many species, it is the orifice through which a very long proboscis can be evolved. The intestine runs undivided through the length of the body; and, it seems probable, that, in all, there is an anus. This has been demonstrated in a few species. It is found in some opening well forwards on the ventral surface, and in the posterior extremity in others. There is another, and much larger, aperture in front, behind and underneath the head. Long mistaken for the mouth, this has been usually described of late as genital, but the office is doubtful. In a few genera there are fissures on the sides of the anterior end, which are neither respiratory nor ovarian, as has been supposed. All are marine, and are readily distinguished, in their order, by their length, which exceeds the breadth considerably, and, in many instances, "far o'ersteps the modesty of nature." The ova are laid enveloped in a jelly. 12. ASTEMMA. Astemma, Oersted, Entw. Plattw. 82. Char. Acephalous, the body filiform, without eyes or fissures on the sides of the anterior extremity: mouth inferior, approximated to the front anus terminal? 1. A. rufifrons, yellowish, verging on rose-red anteriorly; the front obtuse, dark red. Length 2-3"; breadth "". Borlasia (Nemertes) rufifrons, Johnston in Mag. Zool. & Bot. i. 538. pl. 18. f. 4, 5. Dies. Syst. Helm. i. 241. Astemma rufifrons, Oersted, Entw. Plattw. 82. f. 13. Gordius gracilis, Dalyell, Pow. Creat. ii. 74. pl. 9. f. 8-11. Hab. Under stones, and amidst algæ, between tide-marks. (a) Berwick Bay, Dr. Johnston. 2. A. filiformis, white or cream-yellow, thickened in front. Length 1-2". Planaria filiformis, Johnston in Zool. Journ. iv. 56. Borlasia? filiformis, Johnston in Ann. & Mag. Nat. Hist. xvi. 434. pl. 15. f. 1 a, b. Dies. Syst. Helm. i. 242. Hab. Under stones, in muddy places, between tide-marks. 13. CEPHALOTRIX. Cephalotrix, Oersted, Entw. Plattw. 81. Dies. Syst. Helm. i. 246. Char. Acephalous, the body filiform or flattish: mouth anterior, ventral: no lateral fissures: eyes two, placed in front on a parallel line. 1. C. lineatus, filiform, narrower at each end, dark-grey, ruddy in |