FAMILY LITTORACEA. 



183 



Delle Cliiaje in the Bay of Naples, and named by him Helix littorea, 

 since collected by Mr. Metcalfe in the Flete, at Weymouth, and 

 by Professor Forbes in WhitcKff Bay, Isle of Wight, has been 

 pronounced by the last-named author to be an Assiminea, with the 

 same condition of the eyes and tentacles. It has been referred in- 

 differently to Missoa Truncatella and Paludinella. 



The nearest approach to our brackish water Assiminea, so far as 

 regards the shell, appears in India and China. Several allied 

 forms, all of similar habit, have been described from the vicinity of 

 Bombay, under the generic title of Optodiceros ; and others not very 

 far removed, inhabiting tanks, and clumps of damp tree-moss, have 

 been described under the names Tricula and Hydrocena. Of none 

 of these has the structure of the tentacle and eye-stalk been observed, 

 and it is not, therefore, possible to determine their exact relation- 

 ship. Assiminea of the British type is not found in the New World. 

 There is a globose form at Valdivia, Chili, encircled by a linear 

 groove below the suture ; and in North America the genus is re- 

 presented to some extent by certain species of Amnicola. 



Our British Assiminea is : — 



1. Gray ana. Shell pyramidally conical, of six comparatively 

 solid slopingly convex whorls obtusely angled at the base. 



1. Assiminea Grayana. Gray's Assiminea. 



Shell ; pyramidly conical, rather solid, with a minute nearly closed 



umbilicus, fulvous red, translucent, 



whorls six, slopingly convex, obtusely 



angled at the base ; aperture rather 



small, ovate, outer lip simple, colu- 



mellar lip moderately callously ex- 



pandedly reflected. 

 Assiminea Orayana, Leach (1816), Moll. Brit. 



Syn. ined. {fide Gray). 

 Nerita ( Syncera) hepatica, Gray (1821), Lond. 



Med. Repos. p. 239. 

 Assiminea Grayana, Fleming (1828), Brit. Anim. p. 275. 

 Limneus Grayanus, Jeffreys (1830), Trans. Linn. Soc. vol. xvi. p. 378. 

 Paludina Grayana, Potiez andMichaud (1838) Mo 11. Gall. deJJouai, vol. i. 



p. 251. pi. xxv. f. 23, 24. 

 Truncatella Grayana, Clarke (1855), Ann. Nat. Hist. ser. ii. vol. xvi. p. 115. 



