CYMBIUM. 79 



channeled shoulder and want of coronal spines. When fresh, 

 the epidermis is more or less covered by a thin glaze deposited 

 by the enveloping mantle. 



Gray, Reeve and Sowerby have published monographs of this 

 genus ; the two latter with illustrations. For the figures of 

 CymMum, Melo and Voluta, in the present work, I am mainly 

 indebted to Sowerby 's Thesaurus ; they are usually much reduced 

 in size, but the dimensions of the species are indicated in my text. 



C. PROBOSCIDALE, Lam. PL 22, figs. 1-4. 



Yellowish brown, or light salmon-color ; epidermis very thin, 

 brown, over which the mantle of the animal deposits a thin glaze; 

 columellar plaits four in the adult, of which the last is small. 



Length, 1 inch to a foot or more. 



W. Coast of Africa. 



C. porcinum, Lam. (figs. 3, 4) is the young of this species, 

 having only two columellar plaits, and the ends of the shell not 

 so attenuately contracted ; it has generally been distinguished as 

 a species with some doubt, but the specimens before me afford 

 good evidence of the gradual evolution of proboscidale from por- 

 cinum. Between the glaze and the epidermis particles of sand 

 and even small organic bodies are frequently imprisoned ; the 

 former giving the surface a minutely pustulate appearance. 



C. RUBIGINOSUM, Swains. PI. 22, fig. 6. 



There is some little difference of form between this and the 

 last species, but I scarcely think them distinct. It was referred 

 to Australia by Sowerby, and misunderstood and made a synonym 

 of C. cymbium (not of Linn) by Dr. Gray = G. cisiuvn, Lam. 

 Its true locality is N. W. Coast of Africa. Length, 4*5 inches. 



C. CISIUM, Lam. PI. 22, figs. 5, 7, 8. 



Shell light yellowish brown, elegantly marbled with chestnut. 



Length, 3-5 inches, 



W. Africa. 



Gray and others have referred C. cymbium , L., to this species, 

 but the evidence given by Mr. Reeve that the true G. cymbium 

 = C. proboscidale is pretty conclusive.* G. gracile, Brod. 

 (figs. 5, 8), appears to be a form of this shell. 



* Ann. Mag. N. Hist., 3d ser. vii, 271. 



