CONCHOLOGY. 119 



C. nodulosura. C. cressum. 



C. obeliscum. C obtusum. 



&. aluco. C. asperum. 



C. giganteurn. C. vertagum, 



C. sulcatum. C. literatum. 



C. ebeninum. C. heteroclites. 



C. vulgatum. C. semiferrugineum. 



C granulatum. C. tuberculatum. 



C. echinatum. C. ocellatum. 



C. subulatum. C. atratum. 



C. zonale. C. eburneum. 



C. tortulosum. C. lima. 



C. morus. C zonatum. 



0. erythseonense. C. rugosum. 



C. radula. C mitriforme. 



C. decoUatum. C. punctatum. 



C.semigranosum. C. perversum. 



C. lineatum. C. petrosum. 

 C. exasperatum. 



2. Genus Pleiirotoma. PI. XI. 

 Animal. Body oval, spiral above, enveloped in a mantle of 

 which the right edge is furnished with lobes ; foot oval and some- 

 what short ; eyes situated at the external base of long conical, 

 retractile tentacula ; mouth having a long extensible proboscis 

 armed with hooked teeth ; organs of respiration formed by two 

 unequal branchise. 



Shell. Fusiform, a little wrinkled, with a turriculated spire ; 

 a small oval aperture, terminated by a straight canal more or less 

 long, with the right edge trenchant ; a horny operculum. Dis- 

 tinguished from the Cerithium by having a notch in the margin. 

 Twenty-nine living species. Thirty fossil. 



Pleurotoma muricata. Pleurotoma interrupta. 



P. echinata. P. cincta. 



P. flavidula. P. crenularis. 



P. iraperialis. P. unizonalis. 



P. auriculifera. P. lineata. 



P. spirata. P. fascialis. 



