624 APPENDIX. 



Vol. i. p. 335. Genus HYDROBIA. 



The genus Littorinida, described by Eydoux and Souleyet in 

 the " Zoology of the Voyage of the Bonite," ii. p. 536, is syno- 

 nymous with this genus. The species is from Guayaquil, and is 

 named by the French Naturalists Littorinida Gaudichaudii. 



Genus LARINA, A. Adams. 

 (Fam. viviparid^.) 



Operculum annular, horny, ovate, elements concentric ; 

 nucleus intramargiual, near the middle of the inner edge. 



Shell imperforate, semi-globose, thin ; spire obtuse, whorls 

 few, tumid, covered with an olivaceous epidermis, last whorl 

 large and ventricose ; aperture wide, ovate ; outer lip simple, 

 regular, acute. 



Ex. L. Strangei, A. Adams, pi. 137, fig. 9. Operculum, L. 

 Strangei, fig. 9, a. 



The shell on which this genus is founded is from Moreton 

 Bay, in Australia, most probably from some of the fresh-water 

 streams or water-courses in the vicinity. We have referred it 

 provisionally to the Viviparida, until the animal is known or its 

 habits ascertained; the concentric operculum and general ap- 

 pearance of the shell, however, would seem to point out strong 

 affinities with the genera of that family. 



Vol. i. pp. 339 and 340. Genera PALUDOMUS and TANALIA. 



Mr. E. L. Layard has separated the genera Paludomus and 

 TanaUa into four divisions from the peculiarities of the oper- 

 culum, as follows. 



Genus PALUDOMUS, Swainson. 



Operculum with the apex superior and slightly inclined, con- 

 centrically striate; nucleus sub-central, sinistral. 

 Ex. P. chilinoides, Reeve. 



