16 DALYELLID.E. 



Planaria stagni, Dulyell, Pow. Great, ii. 118. pi. 16. f, 30, 

 Planaria foecunda, Daly ell, ibid, pi, 16. f. 31. 



Hah. 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, grass- 

 green. Length ^"'. 



Planaria prasina, Dalyell, Pow. Great, ii. 121. pi. 15. f. 15. 



Hab. Ponds in autumn : gregarious. 



Besc. " 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. ? flustrae, body convex above, flattened below, linear-elongate, 

 rounded and equal at both ends, white, with a dark spot on the 

 neck. Length 2'" ; breadth i'". 



Planaria flustra;, Dalyell, Pow. Great, ii. 118. pi. 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. Plattiv. 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 : 



eyes none. Marine. 



1 . C. paradoxa. 



Planaria convoluta, Abildgaard in Miiil. Zool. Dan. iv. 26. tab. 142. 



f. 4-6. 

 Convoluta paradoxa, Oersted, Entw. Plattw. 75. f. 33, 35, 36. Dies. 



Syst. Helm. i. 218. Schmidt, Neue Rhabdocoel. 5. pi. 1. f. 1. 

 Planaria macrocephala, Johnston in Ann. ^ Mag. Nat. Hist. xvi. 43/. 



pi. 15. f. 2 a, b. 

 Convoluta Johnstoni, Dies. Syst. Helm. i. 219. 

 Planaria haustrum, Dalyell, Pow. Great, ii. 106. pi. 14. f. 36, 37. 



Hab. Amongst confervse 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, 



