OPISTOMUM. TYPHLOPLANA. 15 



Char. Body flattened ; the mouth ventral, subcentral, encircled 

 with a broad annular sphincter : eyes two, approximate, on the dor- 

 sum behind the apex and anterior to the mouth. Lacustrine. The 

 ova capsulated. 



1 . M. rostratitm, 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 i'". 



Fasciola rostrata. Mull. Verm. i. ii. 65. 



Planaria rostrata. Mull. 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, Duges in Ann. des Sc. nat. xxi. 79. pi. 2. f. 16. 

 Dalyellia velox, Johnston in Ann. ^ Mag. Nat. Hist. xvi. 438. 

 Mesostoma rostratum. Oersted, Entw. Plattw. 69. pi. 2. f. 26, 37. 

 Mesostomum rostratum. Dies. Syst. Helm. i. 219. 



Hab. Ponds. 



9. OPISTOMUM, Schmidt, 



Opistomum, Diesing, Syst. Helm. i. 233. Schultze, Naturg. der 

 Turhell. 40. 



Char. Body flattish, with an anterior subterminal mouth ; the 

 oesophagus pitcher-shaped, not protrusile : eyes none. Lacustrine. 



1 . Op. serpentina, tongue- shaped, dilated and rounded in front, lan- 

 ceolate behind, white or grey. Length 2'". 



Planaria serpentina, Dalyell, Pow. Great, ii. 122. pi. 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 Planarise. No eyes visible." — Dalyell. 



10. TYPHLOPLANA, ^ArewSer^, 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. 



I . T. foecnnda, nearly Hnear or a little swollen at the middle with 

 obtusely rounded extremities, white. Length ^"', 



