INTRODUCTION. 53 



metus, Scalaria and Delphinula, seem to have been 

 placed in this family by Lamarck, on account of the 

 whorls being distinct from each other. 

 9. Turbinacea (plates, 353 to 371). The shells contained 

 in this family are all more or less globose, or angular, 

 thickened and pearly within. The following genera are 

 included in this division by Lamarck, Solarium, Rotella, 

 Trochus, Monodonta, Turbo, Planaxis, Phasianella, 

 and Turritella. 



10. Canalifera (plates, fig. 372 to 40-1). The numerous 



genera of which this family is formed, namely, Ceri- 

 thium, Pleurotoma, Turbinella, Cancellaria, Fasciolaria, 

 Fusus, Pyrula, Ranella, Murex, Triton, are distin- 

 guished by having at the anterior termination of the 

 aperture, a more or less elongated canal. 



11. Alatos (plates, fig. 402 to 406). These are known by 



having the outer lip more or less expanded and gene- 

 rally a posterior canal leaning towards the spire. The 

 genera are Rostellaria, Strombus, and Pteroceras. 



12. Purpurifera (plates, fig. 407 to 429). In these, the 



canal, if such it may be called, is extremely short, and. 

 turning abruptly backwards, produces a kind of varix at 

 the lower part of the whorl. The genera enumerated 

 in this family are Cassidaria, Cassis, Ricinula, Purpura, 

 Monoceras, Concholepas, Harpa, Dolium, Buccinum, 

 Eburna, Terebra. 



13. Columellata (plates, fig. 430 to 433). The shells of this 



family are emarginated at the anterior extremity of the 

 aperture, and the inner lip is characterized by plates or 

 folds, which, with the exception of those on Columbella, 

 are distinct. The genera are Mitra, Voluta, Jdargi- 

 nella, Volvai'ia, Columbella, the latter of which would 

 be better placed among the Purpurifera. 



