OF MOLLUSCA. / 



has two series of elongated subulate teeth, swollen at the base, and 

 furnished with a denticulated keeled line, like Conus. 



4. DORSANUM. 



Shell ovate ; suture simple ; outer lip simple, acute. Operculum 



? 



1. D. politum, t. 24. f. 12, 13. 



Fam. III. PLEUROTOMIDjE. 



Animal. Mouth exposed. Tentacles close together at the base of 

 the mouth. Eyes adnate to the outer side of the 

 tentacles near the base. Mantle enclosed, with Fig. 3. 



a slit in the hinder part of the outer side. Si- Teeth of Mangeiia. 

 phon produced. Teeth simple ; base rather en- 

 larged (fig. 3). 



Shell spiral, fusiform ; whorls roundish. Aper- 

 ture ovate ; outer lip with notch or groove behind. 

 Operculum horny, annular, rarely wanting. 



The mantle of the specimen in spirits is grooved 

 as if with plaits on the outer lip. 



a. Clavatulina. Operculum semi-ovate, annular; nucleus in the 



centre of the straight front edge (fig. 4). 



1. Clavatula. 



Shell turrited, spire elongate, canal short. 



1. C. bimarginata. 



2. C. imperialis, Adams, Gen. Moll. t. 10. f. 5, operculum only. 



3. C. muricata. 



2. TOMELLA. Fig * 4 - 



Shell fusiform, canal elongate, inner lip callous 

 near suture. 



1. T- lineata, Swains. Pleurotoma 1., Lamk. ; 

 Adams, Gen. Moll. t. 10. f. 5, operculum 

 (fig. 4). 



b. Pleurotomina. Operculum, ovate, acute ; nucleus apical (fig. 5). 



3. Pleurotoma. 



Shell fusiform, canal elongate, produced ; outer 

 lip with a fissure near the suture. Operculum 

 ovate-lanceolate, flat, front side straight. 



1. P. babylonica, Fig. Moll. t. 1)0. f. 3, t. 90. f. 4. 



2. P. virgo, t. 90. f. 1. 



3. P. oxytropis, Lamk. 



