746 Description of Land and Fresh-water Shells [Nov. 



more lengthened conoid spire. It is very abundant in the river 

 Gumti at Junpur, where it is paler, and has a more yellowish tinge 

 than the Silket variety, which, from having an eroded summit, appears 

 to have inhabited stagnant water. It has a singular habit, for the 

 genus, of burying itself in the mud or sand in shallow water, often in 

 large societies ; other species conceal themselves in the mud in the 

 season of drought, but P. crassa does so from choice, and is impelled 

 by no such necessity. The shell of the lately excluded young is so 

 depressed and globular, that it might be easily mistaken for a young 

 Ampullaria. The adult shell attains a degree of thickness unusual in 

 the genus. 



27. Paludina pulckella. Valvata, No. 9, Hutton, J. A. S. vol. iii. 

 p. 90. 



Testa ovato-conica leviter striata, epidermide olivacea ; anfractibus 

 rotundatis, suturis depressis. Aperturse peritremate nigrescente ; 

 umbilico arcto. Long. 0.3 poll. 



Aperture occupying half the length of the shell. 



28. Ampullaria. The specimens of this shell, which is common 

 in Bengal, are much superior in size to any which I have met with 

 west of the Brahmaputra. As I have reason to believe that the species 

 is described, I shall content myself with this allusion to it. 1 should 

 have considered it to be A. fasciata of Lamarck, were it not that 

 that species is said to have a corneous operculum. 



29. Melania variabilis. Testa elongato-turrita solida olivacea 

 vel picea, sub epidermide albida; anfractibus convexis transverse 

 liratis, longitudinaliter striatis et costatis ; costulis anfractus ultimi 

 superne nodulosis ; apice plerumque truncato ; suturis excavatis. Aper- 

 tura intus violacea, columellae basi sinuata. 



Inhabits the river Gumti at Jonpur, and Tolly's nullah near 

 Calcutta. 



Var. A. Anfractuum inferiorum liris elevatis, nodulis elevatioribus. 

 Inhabits river Hiiohli at Calcutta. 



Var. B. Liris, mediana excepta, obsoletis; nodulis subspinosis 

 carinam humeralem coronantibus. 



Var. C. Lsevis liris costulisque obsoletis, anfractus ultimi medio 

 subcarinato, adulti nodulis humeralibus frugaliter sparsis. 



Var. D. Anfractuum superiorum costulis obsoletis, ultimi et penul- 

 timi liris transversis costulis longitudinalibusque superne serie duplici 

 nodulosis. 



Varieties B, C, and D are in the Silhet collection. The type spe- 

 cimens of several of these varieties would, if viewed apart, be easily 

 mistaken for distinct species, but they melt into each other so gradu- 



