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Turritella. Shell turreted, not pearly; aperture rounded, entire, the 

 margins disunited at the upper part; a sinus in the right lip. Operculum horny. 



T. dtiplicata, 

 ' terebra, 

 ' imbricata, 

 ' replicata, 



T. fuscata, 

 ' cornea, 

 ' brevialis, 

 ' bicingulata, 



T. trisulcata, 

 ' exoleta, 

 ' catinifera, 



' australis, 



T. Virginiana, 

 ' saturalis, 

 12 fossil species. 



SECTION II. TRACHELIPODA ZOOPHAGA. 



Shell spirivalve, ensheathing; aperture either canaliculated, notched, or in- 

 clined at the base. 



There are five families in this section, viz. Canalifera, Alata, Purpurifera, 

 Columellaria and Convoluta. 



CANALIFERA.— Eleven Genera. 



Shell with an canal more or less long, at the base of the aperture, the right 

 lip of which does not change its form by age. 



This family is divided into two divisions. 



DIVISION I. No constant varix on the right Up. 



Cerithium. 

 base by a short, 

 at the upper extr 



C. gitranteum, 



' palustre, 



' sulcatum, 



' telescopium, 



' ebeninum, 



' nodulosum, 



' vulgatum, 



' obeliscus, 



' granulatum, 



' aluco, 



' echinatum, 



Shell turreted; apert 

 truncated or recurved 

 emity of the right lip. 



C. erythraeonense, 



' muricatuin, 



' radula, 



' cressum, 



' decollatum, 



' obtusum, 



' semigranosum, 



' asperum, 



' lineatum, 



' vertagus, 



' fasciatum, 



ure oblong, oblicme, te 

 canal, never notched; 

 Operculum small, orbic 



C. snbulatum, C. 



' heteroclites, ' 



' zonale, 



' semiferrugineum, ' 

 ' tortulosum, 

 ' tuberculatum, 

 ' morns, ' 



' ocellatum, ' 



' literatum, ' 



' atratum, 60 



rminared at the 

 a small channel 

 ular and horny. 



eburneum, 



punctatum, 



lima, 



perversum, 



zonatum, 



petrosum, 



rugosum, 



exasperatum, 



mitriforme, 



fossil species. 



Pleurotoma. Shell turreted or fusiform, terminated at the lower part 

 by a straight canal, more or less elongated. A fissure or sinus in the upper 

 part of the right lip. 



P. imperialis, 

 ' auriculifera, 



P. muricata, 

 ' echinata, 



P. flavidula, 

 ' interrupta, 



P. crenularis, 

 ' cincta, 



