184 PLEUROTOMID^. 



scarcely any anterior canal ; internal lip with a thick posterior 

 callus ; external lip thick within. P. pulchra^ Gray (Ivii, 19). 



CLAVUS, Montf. Tuberculated or spiny ; aperture rather large ; 

 internal lip smooth ; outer lip produced below the sinus. P. 

 auriculifera, Lam. (Ivii, 20). 



ANCiSTROSYRTNX, Dall. (Candelabrum, Dall.) Shell with the 

 posterior surface of the whorls concave, with a broad deep sinus, 

 boi'dered externally by a pectinated elevated frill, directed back- 

 wards. P. elegans, Dall. West Indies. 



BELA, Gray. Shell oval, fusiform, thin ; spire produced ; canal 

 short ; sinus small, near the suture ; columella flattened ; oper- 

 culum pointed at i)oth ends. Northern. P. turricula, Montf. 

 (Ivii, 21). 



BELOMiTRA, Fischer, 1882. Shell like Bela, but with numerous 

 plicae on the columella. B. 2M7'adoxa, Fischer. Atlantic O., 62T 

 metres. 



LACHESis, Risso. (Anna and Ncssea, Risso. Atoma,Bellardi?) 

 Turriculated, with convex whorls and mammillated apex; lip- 

 sinus obsolete ; operculum unguiform. Animal with converging 

 tentacles, short siphon and short ovate foot. P. minima, Montf. 

 (Ivii, 22). 



CLAVATULA, Lam. (Clavicantha, Swainson. Mesochilostoma, 

 Seely?) Subfusiform; spire produced ; whorls coronated ; aper- 

 ture oval ; canal short ; columella smooth, sinuous ; lip-sinus 

 profound. P. imperialis, Lam. (Ivii, 23). 



CLIONELLA, Gray. Shell fusiform, longitudinally ribbed ; last 

 whorl usually contracted in front ; a more or less developed 

 anterior canal ; and posterior sinus. South Africa. A Melania- 

 like shell, usually classed with Pirena, etc., and erroneously sup- 

 posed to inhabit fresh waters. The eyes are placed near the tips 

 of the tentacles, the foot is broad and very short. Operculum 

 subelliptical with the nucleus near the middle of the inner side. 

 Dentition, I'l-l. P. buccinoides, Lam. (Iviii, 24). 



PERRONA, Schum., 1817. (Tomella, Swains.) Shell fusiform, 

 subclaviform ; spire more or less elevated, smooth or carinated; 

 aperture somewhat narrow, terminating in a rather long canal ; 

 inner lip callous near the suture. P. lineata, Lam. (Iviii, 25). 



CLiNURA, Bellardi. Ovately fusiform or turreted ; sinus deep, 

 arcuate ; lip greatly produced anteriorly, aliform ; columella 

 contorted ; canal rather long, oblique. P. Calliope, Brocchi 

 (Iviii, 27). 



CLATHURELLA,Carp. (Defrancia, Millet. Homostoma, Bellardi. ") 

 Fusiform or turriculated ; columellar lip without callosity except 

 a small posterior tooth. No operculum. The cancellated surface, 

 more ventricose form and more evident canal distinguish it 

 from Mangelia, the emargination of the outer lip from Clavatula, 



