POLYCELIS. 9 



circular mouth is on the ventral surface near its centre ; and the 

 proboscis is often extruded when hunger presses, and food is prof- 

 fered. The eyes are separate, either in a linear series or in pairs. 

 The motion is quick and continuous. The food is derived from other 

 soft animals or from the parenchyma of plants. They have great 

 powers of repairing wounds, and of reproducing amputated parts. 

 They are not subject to diffluence in dying. They multiply both 

 by self-division and by ova, which are included within a coloured 

 capsule previous to their exclusion, and for some time afterwards. 

 They pass through no metamorphosis. Lacustrine and marine. 



4. POLYCELIS, Ehrenberg, 1831. 



Polycelis, Diesing, Syst. Helm. i. 191. E. Blanchard in Ann. des Sc. 

 nat. viii. 271 (1847). 



Char. Body flattish, oblong, even and smooth, with a linear series 

 of eyes around the anterior margin which is truncate : oral proboscis 

 long and cylindrical, with a plain orifice. Lacustrine. 



1 . P. nigra, of a uniform velvet-black colour, the front sinuated 

 with two marginal and a central projection. Length 5'" ; breadth 

 I2 • 



Liniaces aquatiques noires, Trembley, Mem. Polyp. 127. pi. 7. f. 9 

 (1744). _ 



Fasciola nigra, Miill. Verm. i. ii. 54. 



Planaria nigra, Miill. Zool. Dan. Prod. 221 ; Zool. Dan. iii. 48. 

 tab. 109. f. 3, 4. Turt. Gmel. iv. 61. Turt. Brit. Faun. 128. 

 BosCf Vers, i. 297. Dalyell on Planarice, 23. f. 3-5, and 15. John- 

 son in Phil. Trans. 1825, 254. pi. 16. f. 9-11. Lam. An. s. Vert. 

 iii. 178 ; 2de edit. iii. 606. Duges in Ann. des Sc. nat. xv. 143. pi. 4. 

 f. 10, 15. W. Thompson in Ann. ^ Mag. Nat. Hist, xviii. 389. 

 Oersted, Entw. Plattw. 54. Dalyell, Pow. Creat. ii. 122. pi. 15. 

 f. 18, 19 (the ova). 



Hirudo nigra, Kirhy in Linn. Trans, ii. 317. 



Planaria fusca, Penn. Brit. Zool. iv. 68 (1812). 



Polycelis nigra, Diesing, Syst. Helm. i. 191. 



Hab. Lakes, ditches and rivulets, in pure water, everywhere. It 

 attains a greater size in stagnant than in running water. 

 («) The Whiteadder, Berwickshire, Dr. Johnston. 



2. P. bniimea, dusky brown, with a dark mesial line ; obtusely tri- 

 angulate in front. Length 4-5'" ; breadth l^'", 



Fasciola brunnea, Miill. Verm. i. ii. 54. 



Planai'ia brunnea, Miill. Zool. Dan. Prod. 221. Turt. Gmel. iv. 61. 



Bosc, Vers, i. 298. Johnson in Phil. Trans. 1822, 438. pi. 49. 



f . 3 & 12. Baer in Nov. Act. Curios, xiii. 706. tab. 33. f. 7. 

 Planaria paniculata, Dalyell, Planar. 37. f. 6, 7- 

 Polycehs nigra, var. brunnea, Dies. Syst. Helm. i. 192. 



Hab. Ponds. 



