1879.] NATURAL SCIENCES OP PHJ LADELPHIA. 29 



striata. Cyclosloma exigua, Homb., also from the Gamblers, 

 probably belongs to the same genus. 



Mr. Pease, in his description of the genus, remarks, from obser- 

 vations made by me that the animal was destitute of tentacles. 

 Since the above was published, I have verified my former obser- 

 vations by a careful study of many examples of both striata and 

 parva. 



The animal is translucent, and, excepting the large conspicuous 

 black eyes, is colorless in both species. The foot is small, oblong, 

 rounded behind, and during locomotion is nearly or quite concealed 

 by the shell, which is carried diagonally. The head, which is en- 

 tirely destitute of tentacles, is produced into a short blunt muzzle, 

 which sometimes assumes a slightly bi-lobed appearance. When 

 creeping, only the extreme tip of the muzzle is seen from above, 

 while the conspicuous eyes are plainly visible through the trans- 

 parent shell. 



Helicina minuta, Sowerby. 



Helicina minuta, Sowerby, Proc. Zool. Soc. 1842, p. 7; Thes. p. 13, 

 pi. 1, fig. 40-41. 



This small species is very abundant, and agrees in every respect 

 with Tahiti and Moorea examples. It is not found on any of the 

 other islands of the Society group, though several species inhabit- 

 ing the other islands are usually confounded with minuta, one of 

 which is described by Dr. Pfeiffer under that name. 



Sowerby's type specimens were collected at Rurutu by Mr. 

 Cuming. His diagnosis, though very brief, accords well with the 

 shells before me. The size he gives is also precisely the same. 

 The shell described by Pfeitfer, which is larger, is, as near as I 

 can determine, one of Mr. Pease's unpublished species, which in- 

 habits Raiatea. 



Assiminea nitida, Pease. 



Mydroeena nitida, Pease, Proc. Zool. Soc. 1864, p. 674. 

 Hydrocena parvulu, Mousson, Jour, de Conch. 1865, p. 184. 

 Assiminea nitida, Pease, Jour, de Conch. 1869, p. 165, pi. 8, fig. 11. 

 Assiminea lucida, Pease, Jour, de Conch. 1869, p. 166, pi. 8, fig. 10. 

 Omphalotropis parvula, Paetel, Cat. Conch. Sara. p. 124. 

 Hydrocena similis, Baird, Brenchly's Cruise of the Curacoa. 



This small species ranges from the Marquesas and Paumotus 

 to the Yiti Islands. 



