92 CANALIFfiRA- 



is in some species cup-shaped, in some it juts out of the centre in 

 a double point ; in others it is only a small flap ; and in others 

 a spiral disc. These last, which are shaped like Trochus, are 

 separated by De Montfort under the appellation Infundibulum ; 

 Trochatella, Sw. The Calyptraea may be known from Crepi- 

 dula by the septum, which in the latter is a flat plate reaching 

 half way across the cavity. Fig. 234, 5, 6. 



CAMERINA. Brug. Nummulites, Auct. 



CAMILLUS. Montf. A genus founded upon a minute spiral 

 shell, with a triangular aperture, turned over the back of the 

 last whorl. It is figured in Soldani's Testacea Microscopica. 



CAMPULOTUS. Guettard. Magilus, Auct. 



CANAL. A groove which characterizes some spiral univalves, 

 where the inner and outer lips unite at the front part of the aper- 

 ture. This canal is drawn out in some shells to a considerable 

 lengthj in others it is turned abruptly over the back. The family 

 Canaliferae, Lam. (fig. 372 to 401), are all provided with this 

 canal. 



CANALICULATED. Applied generally to any distinct groove or 

 canal. 



CANALIFERA. (Canalifires, Lam.) A family belonging to the 

 order Trachelipoda, Lam. nearly corresponding with the family 

 Entomostomata in De Blainville's system, and described as having 

 a canal of greater or less extent at the anterior part of the aper- 

 ture . This canal is sometimes straight, sometimes tortuous, and 

 in some genera it is recurved over the back of the shell. All the 

 shells have an operculum, and the thickness of the perfectly 

 formed outer lip does not increase with age. The Canalifera are 

 characterized by having a canal, in distinction from the Pur- 

 purifera, which have only a notch. This family contains the 

 following genera, 



1. Cerithium. Club-shaped. Fig 372. 



2. Potamis. The same, fresh water. Fig. 377. 



3. Nerinea. The same, with internal folds. Fig. 374. 



4. Triphora Anterior and posterior canals closed so as 

 to present three openings. Fig. 375, 376. 



