118 CREITHIIDJE. 



prolonged in front. Ocular peduncles long, tentacles not visible. 

 P. CHARBOXNIERI, Petit (PL 19, fig. 5.). Von Martens suspects 

 that the ends of the tentacles are bent back when the animal is at 

 rest so as to become invisible ; at least this is the case in Potamides 

 obtusus (Archivfur Naturgeschichte, li, 48). 



Subgenus LAMPANIA, Gray, 1846. 



Turriculated, a little curved, whorls without varices; aperture 

 subtruncate at the base, with a scarcely distinct, straight canal ; 

 lip sinuous. P. ZONALE, Lam. China. 



Batillaria, Cantor, 1842, is the same, and has priority; but 

 Lampania is well established, and need not be changed. 



Section LAMPANELLA, Morch, 1876. 



Shell small, decussated. P. MINIMUS, Gmel. 



Subgenus ESCOFFIERIA, Fontannes, 1880. 



Turriculated, narrow, whorls numerous, subsolute ; aperture sub- 

 circular, with sharp lip, columella excavated, canal obsolete. P. 

 FISCHERI, Fontannes. Upper Tertiary of the Rhone basin. 



? Genus SAISTDBERGERIA, Bosquet, 1860. 



Shell small, ornamented like Bittium, with a rudimentary broad, 

 shallow, short canal, lip curved, prominent at the base, columellar 

 extremity surrounded by a basal fasciole. Operculum said to be 

 concentric and calcareous, but there is some doubt about this : if it 

 is so, the group is certainly out of place in Cerithiidse. S. ANTE- 

 CEDENS, Stol. Tertiary. 



Genus DIASTOMA, Desh., 1848. 



Turriculated, with numerous ribs and a few varices ; inner mar- 

 gin of the aperture partially detached from the previous whorl, the 

 aperture is strongly contracted posteriorly, sinuous and subangular, 

 but not channeled at the base, channeled behind, columella con- 

 cave, simple. 



D. VARICULOSUM, Desh. (Struct, and Syst. Conch., t. 72, f. 50), 

 Eocene. 



? Genus MESOSTOMA, Desh., 1861. 



Subrimate, elongated, turreted ; aperture nearly circular, dilated, 

 oblique, terminating in front by a semicanaliculated angle; 

 columella slightly concave, lip simple, slightly expanded. 



M. GRATUM, Desh. Eocene, Paris basin. 



