CASSIDAIUA. MOLLUSCA. 35 



gose. 3 inches long. Inhabits the intertropical seas. Lister, 

 pi. 1001, fig. 66. 



Gen. 22. CASSIDARIA, Lam. Buccinum, Lin. 

 Shell obovate or oblong ; aperture longitudinal, narrow, end- 

 ing below in a somewhat ascending curved canal ; outer lip 

 marginate, or folded back at the margin ; inner lip cover- 

 ing the columella, more frequently rough, granular, tubercu- 

 late, or rugose. 



The Cassidariae are marine shells. They are closely allied to the preceding ge- 

 nus, but are sufficiently distinguished from it by the difference in the form and in- 

 clination of the canal. 



C. echinophora, Lam. Shell ovate, ventricose, with transverse ele- 

 vated striae and four tubercular belts ; whorls of the spire angu- 

 lar, the angle crenated with tubercles ; colour pale brown. About 

 4 inches long. Inhabits the Mediterranean sea. Bonan. 3. 

 fig. 18, 19. 



C, oniscus, Lam. (Strombus, Lin.) Shell ovate, thick, with three 

 transverse nodose ribs, variegated with white and brown, red 

 below ; spire very short ; columella granulated; outer. lip inter- 

 nally dentate and sulcate. 1 inch long. Inhabits the seas of 

 America Lister, pi. 791, fig. 44. 



FAMILY IV ALATA. 



Shell with a canal of greater or less extent at the base of the 

 aperture, of which the right lip changes its form as the ani- 

 mal advances in age, and has a sinus at the lower part. 



The Alata constitute a. very natural family. It presents a fact which is very un- 

 common, the shell in its younger state being of a different form from what it is when 

 adult. There are only three genera in this family ; Strombus, Pterocera^ and J?o- 

 tellarid) which together constituted the genus Strombus of Linnaeus, 



Gen. 23. STROMBUS, Lin. 



Shell ventricose, terminating at the base in a short emarginate 

 or truncate canal ; right lip dilating with age into a simple 

 entire wing, lobed or crenated above, and having a sinus be- 

 neath, separated from the canal or notch of its base. 



The Strombi live in the seas of warm climates. Many species are of moderate 

 and even small size, but others become very large. They are distinguished generi- 

 cally from the right lip being much dilated and entire, and by the canal at the base 

 being very short, truncated or notched. 



S. gigas, Lin. Shell turbinate, ventricose, transversely rugose, yel- 

 lowish white ; upper part of the whorls crowned with low conical 

 spreading tubercles; lip extremely broad, rounded above; aperture 

 smooth, rose-colcured. 10 inches long. Inhabits the seas of the 

 West Indies Lister, pi. 863, fig. 18, b. 



S. gallus, Lin. Shell turbinate, tuberculated, transversely sulcate, 

 variegated with white and red ; the last turn crowned above with 

 large compressed tubercles; tubercles united by a transverse 

 ridge ; lip thin, extended above into a long lobe. 4^ inches long. 

 Inhabits seas of Asia and America. -*~Bonan. 3. fig. 309, 310. 



