BY C. HEDLEY. 159 



" The above genus," observes Pease, " was established by Dr. 

 Beck on Helix oparica, Anton, from the collection made by the 

 late Mr. Cuming at the island of Rapa (Opara), one of the Austral 

 group, a few hundred miles south of Tahiti. There is no doubt as 

 to the identity of the species, although it was described by Dr. 

 Anton as H. oparica from America. By reason of the similarity 

 between the shells of certain species discovered since and those of 

 the European genus Discus, Fitz., = Patula, Held., all the Poly- 

 nesian forms have been described under the European genus ; 

 with few exceptions the shells are quite distinct and the animal 

 decidedly so ; they are most numerous at the Hawaiian and 

 Tahitian Islands, less so at the Samoas, and altogether absent 

 in West Polynesia." 



Nevill (Hand List Mollusca, Indian Museum, Pt. I. p. 69) 

 misquotes H. contorta as the type of Pitys. 



Allied to Pitijs is the genus Endodonta, Albers, type £. lamellosa, 

 Ferussac, created for the reception of species from the Society and 

 Sandwich A.rchi|)elrtgos. The description, "Die Heliceen," 2nd ed. 

 p. 90, runs as follows : — 



Endodonta, Albers (1850). 



" Testa umbiiicata vel perforata, depressa, discoidea vel orbicu- 

 lato-convexa ; anfractus 5-S arete voluti ; apertura rotundato- 

 lunaris vel saepius angulata, rarissime simplex, plurumque in 

 pariete ventrali lamellata, vel etiam margine basali lamellato- 

 dentato, peristoma rectum, acutum." 



Nearly related to the preceding is the genus Libera, Garrett. 

 No type is named, but the first species, which may be considered 

 such, is L. fratercida, Pease. 



This genus was defined by Garrett (Journ. Acad. Nat. Sci. 

 Philadelphia, Ser. 2, 1881, p. 390) in the following terms: — 



Libera, Garrett (1881). 



" Shell small, widely umlulicated, umbilicus (in adults) strongly 

 constricted so as to form a cavernous or pouch-like cavity ; whorls 

 7-9, costulate or striate, last one angulata or carinate, rarely 



