UNIVALVES. 



PLATE XXXVI. 



Genus. CERITHIUM. 



Character. Shell turreted ; the opening oblique, and ending at the base in a 

 channel cut short by a sudden recurvature ; lip ending at the top in a distinct chan- 

 nel ; mouth labiated all round ; spire long, and irregularly bulbous. 



Species. 



No. 1. Cerithium ferruginosum. Shell tapering and pointed; the mouth open, 

 patulous ; the cheek very much expanded ; the whole colour of the shell of 

 a rusty brown, except the lip, which is nearly white. This shell is very 

 rare, and is found in the East Indies only. 



No. 2. Cerithium spicatum. Shell of a bright reddish brown, ornamented with 

 rounded spikes, or tubercles placed in rows upon the spire ; the mouth yel- 

 low within, the lips white. It is thought to be a native of the Cape of Good 

 Hope. From a shell in Dr. Lettsom's Museum. 



No. 3. Cerithium fuscum. Shell brown, variegated with shades of blue ; mouth 

 blue ; the folds of the spire undulated with waving lines. This shell is 

 larger than most others of this genus, and is brought from the West Indies 

 and Madeira. 



No. 4. Cerithium bandatum. Shell gray, inclining to white ; the spire orna- 

 mented with bands of a red colour, running round the folds ; the mouth 

 brown, edged with white ; the spire smooth, and without tubercles. Native 

 place unknown. 



No. 5. Cerithium turriformis. Shell of a buff colour, irregularly shaded with 

 dark brown streaks ; the mouth brown, and the lips white. This shell is 

 remarkable for the soft and pleasing effect of its colouring, and is generally 

 brought from the East Indies, where, it is said, they are found only on the 

 deepest and most rocky shores. 



REMARKS. 



The Cerithium has a strong analogy to the Rostellaria in the spire and channel belonging 

 to the top of the mouth, but differs from it in the beak and maxilla oris, which are not decus- 

 sated in this genus. It differs obviously from the Turbo and Terebra genera in the form of 

 its mouth and beak, and, what is very singular, is not met with in the European Seas. Fossil 

 shells of this genus, deposited, as it is supposed, in former ages by the Deluge or some other 

 great convulsion of nature, are found in immense quantities, and variety of species, in the in- 

 land mountains of France, Germany, and England ; but, after a careful examination of their 

 forms, they are found to be totally different in their shape, and must be considered as distinct 

 individuals. What makes the circumstance the more extraordinary is, that the number of 

 species of this genus, amongst the recent ones, are very few, whereas the variety and quan- 

 tity of the fossil species are immense. But it would be taking the Reader too far from the 

 present subject to enter in this place into farther reflections upon these phenomena, which 

 may perhaps more properly form the subject of a future and distinct work. 



