PALUDINID^. 891 



BiTHYNIA MORELETIANA, Nevill. 

 Bithynia moreletiana, Nevill, Journ. As. Soc, Bengal, vol. xlvi, 1877, p. 29. 



In shape resembling B. lutea, Gray^ spire peculiarly short, apex very obtuse 

 and flattened, always eroded, but not decollated; whorls SJ, the last obliquely 

 produced ; always imperforate, both in very young and very old shells ; margins of 

 aperture entire, broadly reflected, produced and angled at base ; outer margin 

 rounded; epidermis dark olive- green; under the lens a minute spiral sculpture can 

 be detected. Young specimens invariably show a sort of varix, formed probably 

 at a period when their growth is arrested by some cause ; this varix becoming 

 absorbed in adult specimens. Above 200 specimens were found at Yaylaymaw. 



Long. max. 8f , min. 7}, diam. max. 6, min. 7f mm. ; long, anfract. ult. 7 ; 

 long, apert. 5}, diam. 3 mm. 



This species can easily be distinguished from the Indian B. cerameopoma and 

 B. lutea : it is imperforate, has fewer whorls, a shorter and more obtuse spire, the 

 columellar margin is less acutely angled at base, epidermis green instead of brown. 



Genus Margaeya, Nevill.^ 



This remarkable shell is very difficult to classify, owing to its great analogy to 

 two fresh- water genera, Baludina and Melania. I think, however, there is little 

 doubt but that it will have eventually to rank as a sub-genus of Paludina. 

 Margarya is characterized by its produced, Melania-like spire, composed of scalari- 

 f orm, rapidly increasing whorls, with very distinct suture ; apex obtuse, sculptured 

 with prominent spiral ribs ; rimate (or umbilicate ?) ; margins of aperture rounded, 

 not continuous ; animal and operculum unknown. 



Maegarta melanioides, Nevill. Plate LXXX, fig. 5.^ 



Margarya melanioides, Nevill, Journ. As. Soc, Bengal, vol. xlvi, 1877, p. 30. 



Shell large ; spire produced, Melania-like, with very deeply excavated suture ; 

 apex obtuse ; whorls six, convex, the first two flat and obtuse, the third large and 

 tumid (bigger in proportion than the fourth) ; the four last whorls are girt with 

 three nearly equally distant, raised, irregularly nodulose keels, the middle one much 

 the largest, having its nodules more developed and of a more or less compressedly 

 transverse shape ; umbilicus very small, almost entirely covered by the reflected 

 columella; aperture almost circular, nearly as broad as high; columella short, 

 evenly rounded, moderately reflected over the shallow umbilicus ; a slight callus 

 between the columella and outer lip ; remains of an epidermis distinctly traceable. 



1 Cou. Indica, pi. xxxvii, fig. 7. 



2 Journ. As. Soc, Bengal, vol. xlvi, 1877, p. 30. 



3 Mr. Nevill first named this shell Paludina margariana, and as such it stands in the accompanying plate, which 

 was printed before Mr. Nevill was led to regard this tine form as distinct from Paludina. 



