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II. Order. BDELLOMORPHA. The posterior extremity of the body with a sucker-like circular disc or with several discs.

V. Order. GYMNOCOPA. The body hyaline and furnished with a series of compressed fins along each side: head distinct, with tentacular processes.

** Body annular.

III. Order. BDELLIDEA. The anterior and posterior extremity with a sucker-like circular disc.

B. POLYPODOUs: the body with bristles along the sides. Chetopodes, De Blainville. Polypoda, Macleay. Chathelmintha, Diesing.

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IV. Order. SCOLOCES. Body vermiform, without external soft appendages; the segments with simple spiniform or setaceous bristles, either single or fasciculate.

VI. Order. ANNELIDES. Body vermiform, with soft external appendages, and with various bristles collected into fascicles on a more or less protuberant basis.

Order I. TURBELLARIA.

PLANARIA, Müll. Zool. Dan. Prod. xxviii. (1776). Bosc, Vers, i. 290 (1827).

PLANAIRES, Cuv. Règn. Anim. iii. 266.

APOROCEPHALA, Blainville in Dict. des Sc. nat. lvii. 573 (1828).
PLANARIEE, Dugés in Ann. des Sc. nat. xv. 140 (1828).

TURBELLARIA, Ehrenberg. See Lam. An. s. Vert. 2de edit. iii. 608.
Agassiz, Nom. Zool. Verm.

NEMERTINA, Macleay in Murchison's Silurian Syst. ii. 699 (1839),
and in Ann. Nat. Hist. iv. 385.

MOLLUSCA PARENCHYMATA, Swainson, Malacology, 35.

PLANARIÆ, Jones' Anim. Kingd. 89.

PLANARIÉES, M.-Edwards, Elem. Zool. 2de edit. ii. 230.

VERMES, Dalyell, Pow. Creat. ii. 53 (1853).

TURBELLARIEA, Diesing, Syst. Helm. i. 179.

PLATTWURMER, Oersted, Entwurf Plattw. 1. (1844).

Char. Worms individual, locomotive, very rarely tubicolous, monœcious or diœcious, with or without eyes, the surface usually coloured and sometimes in elegant patterns, transparent or opake. Body soft, parenchymatous or cavernous, flat or subcylindrical, naked and lubricous, covered more or less with vibratile cilia, and sometimes with

papillæ; often very contractile and polymorphous, and some breaking up voluntarily into pieces. Head continuous with the body, or, rarely, imperfectly defined, either without tentacula or with two frontal or dorsal ones prolonged from the surface. Mouth either terminal or ventral, and in the latter case situated in the anterior third, or near the centre, or towards the tail; often furnished with a protrusile proboscis. Intestine dendritically branched or undivided, with or without an anus.-Zoophagous, but some appear to feed occasionally at least on decaying plants. Oviparous or viviparous, very rarely multiplied by spontaneous division. There are no suckers or discs, and progression is made by gliding or by natation. They are never internal parasites, but tenant fresh and salt water, and are found sometimes in moist places. The skin is very rarely iridescent, and there is no phosphorescent species.

The British genera may be classified in the following manner :—

Suborder I. PLANARIEA.

The body parenchymatous, flat or flattened, usually only a little longer than broad, acephalous, with or without eyes on the dorsum in front mouth a simple pore, often the aperture to a protrusile proboscis anus none: genital pore posterior to the oral.

:

* Intestine dendritically branched.

Family I. PLANOCERIDE. Flat: the mouth nearly in the centre of the ventral surface, and furnished with a short proboscis crenated or lobed at the orifice.

1. Leptoplana. Multocular, the eyes clustered: no tentacula. 2. Eurylepta. Multocular, the eyes clustered: two frontal tentacula.

3. Planocera. Multocular or eyeless: two dorsal tentacula.

Family II. PLANARIADÆ. Flattish: the mouth inferior, subcentral, with a long cylindrical proboscis plain at the orifice. 4. Polycelis. Eyes many, in a marginal series.

5. Planaria. Eyes two, dorsal, and paired.

** Intestine an undivided tube.

Family III. DALYELLIDE. Mouth terminal or subterminal, eproboscidean.

+ Eyeless.

9. Opistomum. Body elongate: mouth terminal.

10. Typhloplana. Body linear-oblong: mouth ventral, subcentral. 11. Convoluta. Body involute.

†† Eyes two.

6. Dalyellia. Mouth terminal.

7. Derostoma.

Mouth ventral, anterior.

8. Mesostoma. Mouth ventral, subcentral.

Suborder II. TERETULARIA.

The body cavernous, linear-elongate, subcylindrical or compressed, very contractile, sometimes breaking spontaneously into pieces, the surface even and smooth, or rarely wrinkled: head more or less distinct, the mouth a simple terminal or subterminal pore, with a very long included proboscis: intestine undivided, laid in the visceral cavity, with the vent situated well forwards, or posterior and terminal? There is a larger aperture below the head which leads to the common cavity.

* Acephalous: the anterior end plain.

12. Astemma. Eyeless.

13. Cephalotrix. Eyes two, parallel.

14. Tetrastemma. Eyes four, in a square.

** Acephalous, with a furrow on each side of the front.

20. Serpentaria. Body flat, elongate, uniformly coloured, fragile. 19. Meckelia. Body linear-elongate, fragile, with paler annulations.

*** Cephalous, the head indistinct, multocular, and mostly with a shallow furrow on each side.

15. Borlasia. Eyes in a submarginal series: œsophagus simple. 16. Omatoplea. Eyes clustered, irregular: the œsophagus with horny stylettes.

17. Stylus. Anal extremity armed with a long style.

**** Ophiocephalous, with lateral furrows.

18. Lineus.

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I. TURBELLARIA.

I. PLANARIEA.

SANGSUES-LIMACES, Reaumur, Hist. Insect, vi. pref. lviii.

PLANARIA, Lam. An. s. Vert.iii. 176. Schweig. Handb. 593. Dalyell,
Pow. Creat, ii. 96 & 125.

PLANARIADÆ, Flem. Phil. Zool. ii. 604.

PLANARIE, Blainville in Dict. des Sc. nat. lvii. 577; Ann. & Mag.
Nat. Hist. xvi. 227.

PLANARINE, Johnston in Ann. & Mag. Nat. Hist. xvi. 436.

ANEVORMI (-), E. Blanchard in Ann. des Sc. nat. vii. 105, 106
(1847); and viii. 119, 141 (1847).

APOROCEPHALÆ, E. Blanchard in Ann. des Sc. nat. viii. 143 (1847).
PLANARIEA, Oersted, Entw. Plattw. 41. Diesing (×), Syst. Helm.

i. 184. Ray Soc. Rep. Zool. 1847, 516.
APROCTA, Schultze, Naturg. Turbell. 3.

Fam. I. PLANOCERIDE.

CRYPTOCŒLA, Oersted, Entw. Plattw. 44. f. 2. p. 12. Rep. Ray Soc.
Zool. 1847, 517.

Obs. The body is thin, flat, and laterally expanded, with a plain margin. The eyes, when present, are clustered. The oral aperture is usually closed and becomes almost indistinguishable, but the position of it, and of the proboscis, is marked by an oblong spot near the middle of the ventral surface. This is always paler than the dorsal, which is commonly beautifully coloured. The motion is slow. The food is soft, either the juices of avertebrate animals or the parenchyma of decaying algae. All are marine, and propagate, probably, by naked ciliated ova, undergoing no metamorphosis. In decay, the body is diffluent; and decomposition has far advanced before life is extinguished.

1. LEPTOPLANA, Ehrenberg, 1831*.

Leptoplana, Oersted, Entw. Plattw. 48. Diesing, Syst. Helm. i. 194.
Prosthiostomum, Quatrefages in Ann. des Sc. nat. iv. 133 (1845).
Polycelis, Quatrefages in ibid. 132.

Char. Body flat, entire, with a smooth dorsum: mouth subcentral eyes in two or four clusters: genital pore behind the mouth.

* When, as in this example, the name of the founder of the genus immediately follows the generic name, the date of the latter rests on the authority of Agassiz's Nomenclator Zoologicus. In these instances, I have not had an opportunity of consulting the original authority.

* Eyes in two clusters.

1. L. subauriculata, body lanceolate, very thin, obtuse in front, of a yellowish-brown colour; eyes numerous, in two clusters, with a clear circular spot to each cluster, and a clear intervening space. Length 6""; breadth 2"".

Planaria subauriculata, Johnston in Loud. Mag. Nat. Hist. ix. 16. f. 2.
Leptoplana subauriculata, Dies. Syst. Helm. i. 195.

Planaria corniculata, Dalyell, Pow. Creat. ii. 101. pl. 14. f. 5.

Hab. The shore between tide-marks.

2. L. tremellaris, body ovate, sinuous on the margin, yellowish, unspotted; posterior eye-clusters on a pale spot, irregular, with a line from each running parallel forwards to a minute ocular spot. Length 8-11""; breadth 3-5"".

Fasciola tremellaris, Müll. Verm. i. ii. 72.

Planaria tremellaris, Müll. Zool. Dan. Prod. 223; Zool. Dan. i. 36. t. 32. f. 1,2; copied by Blainv. Dict. des Sc. nat., Vers, Atlas, f. 14. Turt. Gmel. iv. 67. Bosc, Vers, i. 309. Lam. An. s. Vert. iii. 180; 2de edit. iii. 608. Dugés in Ann. des Sc. nat. xv. 144. pl. 4. f. 14. Grube, Actin. 52. W. Thompson in Ann. & Mag. Nat. Hist. v. 247.

Leptoplana tremellaris, Oersted, Entw. Plattw. 49. Dies. Syst. Helm. i. 198.

Hab. In pools among the rocks between tide-marks, under stones. (a) Rothesay, Miss Macdonell.

** Eyes in four clusters.

3. L. flexilis, body very thin, ovato-lanceolate, widest and semicircular in front, of a dull whitish or pale ash colour; eye-clusters defined by a clear space. Length 7""; breadth 3"".

Planaria flexilis, Dalyell, Planar. 5. pl. 1. f. 1, 2. Johnston in Loud. Mag. Nat. Hist. ix. 17. W. Thompson in Ann. & Mag. Nat. Hist. ser. 2. iii. 354. Dalyell, Pow. Creat. ii. 102. pl. 14. f. 17–26. Polycelis fallax, Quatrefages in Ann. des Sc. nat. iv. 135. pl. 3. f. 10. (1845).

Leptoplana flexilis, Dies. Syst. Helm. i. 194.

Hab. Between tide-marks, generally half-buried in mud: grega

rious.

4. L. atomata, ovate, obtuse, only a little narrower behind, speckled brown; eyes of the anterior clusters more scattered than of the posterior, not seated on a lighter ground. Length 6""; breadth 3"". Planaria punctata, Müll. Zool. Dan. Prod. 2706.

Planaria atomata, Müll. Zool. Dan. i. 37. tab. 32. f. 3,4. Turt. Gmel. iv. 65. Bosc, Vers, i. 305. Fleming in Edin. Phil. Journ. viii. 297.

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