1867.] Contributions to Indian Malacology. GI 



are poor, but the specimens were from Bengal, and they present 

 no essential difference from immature shells of cornucopia, so Mr. 

 Benson is doubtless correct. Beeve in Conch. Icon, quotes N. 

 melanostoma as a synonym of JV. crepidularia and ignores N. cornu- 

 copia altogether. Von Martens (Malakoz. Blatter, 186S, X, 127.) 

 shews that the colour of the columella and lip is sometimes white 

 and sometimes black in several Neritince of the Dostia section. 



The fact very probably is, that we have in this case an example of 

 a phenomenon not uncommon in the animal kingdom. Two distinct 

 races spring up side by side, arising from one type, and in the original 

 locality do not change their form, but although they breed truly, they 

 are only distinguishable by some slight constant distinction. As both, 

 however, migrate into distant regions, the difference becomes greater, 

 and at length both become so diverse, that no question can remain as 

 to their being in common natural history talk, " distinct species.'* 

 Thus while Neritina cornucopia and N. depressa, inhabiting the Ganges 

 delta, are scarcely distinguishable from each other by any more im- 

 portant character than the colour of the aperture, the same shells in 

 Pegu have varied so much, that each differs from the other at least as 

 much as it does from their congener N. crepidularia. In other places 

 the race representing N. cornucopia may be perfectly undistinguish- 

 able from N. crepidularia, as appears to have been observed by v. 

 Martens in Singapore. It is highly probable that the origin of species 

 through variation takes place in space as well as in time. More ob- 

 servations on this question are desirable. 



Figures of the three forms occurring in the Pegu delta are added. 

 Family PALUDINID^E ? 

 No. 21, Larina ? Burmana, n. sp. PL II, fig. 1. 



Testa ovato-globosa, imperforate, tenuis, castanea, striatula, nitidula. 

 Spira conoidea, apice erosula, sutura valde impressa. Anfr. 5, rotunda- 

 ti, sensim descendentes, ultimus tumidus, subtus rotundatus. Apertura 

 vix obliqua, subelliptica, superne angidata ; peristoma rectum, tenue, 

 marginibus callo tenui junctis, columellari expansd. ? Operc. corneum. 

 Long. 11, diam. 8 mill. Apertura 7 J mill, longa, 6 lata. 



Shell ovately globose, imperforate, thin, translucent, smooth, brown- 

 ish, horny. Spire conoidal, apex eroded, suture deep. Whorls 5 

 (perhaps more in adult specimens), rounded, obsoletely striated, regu- 



