OF CONCHO LOOT. 185 



ON THE LINGUAL DENTITION OP BLANDIELLA, GEOME 

 LANIA AND AMPHIBULIMA. 



BY THOMAS BLAND AND W. G. BINNEY. 



Blandiella was described by Mr. Guppy in the American 

 Journal of Gonchology, VI. 309. In speaking of its lingual 

 membrane, Mr. Guppy says it is intermediate between Qyclopho- 

 ridce and Paludinidce. Having received specimens of the ani- 

 mal, we have examined the membrane, and find it much more 

 like that of Truncatella and the fluviatile Rissoidce, sharing with 

 those genera the peculiarity of the basal denticles on the central 

 tooth. The membrane (plate 17, fig. 5) is long and narrow ; teeth 

 3. 1. 3, as usual in the Pectinibranchiata. Centrals somewhat 

 conical, broadly truncated by the reflection of the apex, which 

 is trilobed, the central lobe extended into a short, stout beak ; 

 the infero-lateral extremities are somewhat produced, and bear 

 on their anterior surface four short, triangular denticles, point- 

 ing outwards. The first lateral is about the same height as the 

 central, but much broader ; the upper edge is recurved along its 

 whole length, and bears five denticles, of which the second from 

 the inner edge is the largest and acutely pointed. The second 

 lateral is long, laminar, with a recurved and minutely denticul- 

 cated upper edge. The third lateral is similar to the second, 

 but somewhat more narrow. Fig. 5 gives one central tooth, with 

 the adjacent laterals of one side only of the membrane. 



B. reelusa, Guppy, the species referred to, is from Trinidad. 



Geomelania (pi. 17 fig. 7, 10) has the same characters of lin- 

 gual dentition as already described in Blandiella. The central 

 tooth has, however, less developed infero-lateral expansions ; the 

 basal denticles, two in number, are longer, and point downward 

 rather than outward. Our figure 10 gives one central with the three 

 laterals of one side only of the membrane. A more highly 

 magnified view of a central is given in figure 7. These figures 



