RRITISH MARINE TURBELLARIA. 237 



distance behind this. The penis is pyriform, and receives the contents 

 of a vesiada seminalis and granule-gland. The uterus lies in front and at 

 the sides of the pharynx • it opens to the exterior along with the 

 sperm otheca through the vagina. 



Habitat. — Berwick Bay (Johnston) ; Firth of Forth (Dalycll) ; 

 Firman Bay, Guernsey (Lankester); St. Andrews (Mcintosh); Jersey 

 (Koehler). 



Distribution. — St. Malo (Quatrefages), St. Vaaste-la-Hogue 

 (Claparede). 



Family LEPTOPLANIDvE. 



Mouth and pharynx sub-central. Main-gut usually extends in front of, 

 rarely behind, the "pharyngeal sheath. Branches numerous. Male 

 copulatory organ directed posteriorly. Tentacles absent. Eyes — 

 (1) two lateral groups on the areas representing the tentacles of 

 Planocerida ; (2) double cephalic group; (3) marginal; (4) 

 irregularly disposed over the head. Direct development. 



Genus 29. — Leptoplana, Ehrenberg (10). 



Eeptoplanidce with elongate, delicate body. Pharyngeal sheath long. 

 Lateral pouches numerous. Pharynx not completely folded. 

 Genital apertures distinct. Granide-gland and vesicula seminalis 

 separate. Marginal eyes absent. Eyes of group (1) larger than 

 those of (2). 



62. Leptoplana tremellaris (0. F. Miiller). 



1774. Fasciola tremellaris, 0. F. Midler (2). 



1776. Plan aria tremellaris, 0. F. Mailer (4). 

 1814. „ flexilis, Dalyell (6). 



1840. ,, tremellaris, W. Thompson (15). 



1844. Leptoplana tremellaris, Oersted (16). 



1845. Plan aria flexilis, Johnston (20) 

 1845. PoLYCELIS L^VIGATUS, Quatrefages (18). 

 1849. PLANARIA FLEXILIS, Thompson (25). 

 1853. „ ,, Dalyell (29). 



1865. Leptoplana tremellaris, Johnston (38). 

 1S66. ,, flexilis, Ray Lankester (39). 



1874. „ „ Mcintosh (45). 



1886. „ TREMELLARIS, Koehler (55). 



1886. POLYCELIS L.EVIGATUS Koehler (55). 



