GEOMELANIA. 



311 



the shore, and sometimes in shallow water. In the Corea 

 they live gregariously, by many thousands, in the holes of 

 decayed rock and coral which border, in many places, the 

 Islands ; the spots they occupy are always exposed to the 

 spray of the sea. 



Species of Truncatella. 



Adamsi, Pfeiff. 

 aurantia, Gould. 

 bilabiata, Pfeiff. 

 Caribfeensis, Sow. 

 clathrus, Lowe. 

 crassicostata, Sorv. 

 Guerinii, Villa. 

 Montagui, Loice. 

 porrecta, Gould. 

 pulchella, Pfeiff. 



Quoyi, Pfeiff. 

 rostrata, Goidd. 

 scalariformis, Peeve. 

 scalaris, Mich. 

 striata, Sow. 

 striatula, Mke. 

 truncatula, Drap. 

 valida, Pfeiff. 

 vitiaua, Gould. 



Genus GEOMELANIA, Pfeiffer. 



Operculum horny, sub-spiral. 



Shell imperforate, turreted ; aperture entire, effuse, peri- 

 stome simple, expanded, the margin produced into a some- 

 what-twisted, linguiform appendage. 



Ex. G. Jamaicensis, Pfeiffer, pi. 88, fig. 2. Operculum, 

 G. Jamaicensis, 2, a, 2, b. Shell, G. Jamaicensis, fig. 2, c. 



The animal of Geomelania, first made known by one of 

 the Authors, is very similar to that of Truncatella ; the 

 operculum and shell also closely resemble those of that 

 genus, the principal difference consisting in the persistent 

 apex of the spire, and the prolongation of the outer lip of 

 the shell into a peculiar tongue- shaped process at the fore 

 part of the aperture. In their habitat they appear to be 



