PART II. TBOCHIN^E. 349 



perforate ; both sides compressed ; substance of the 

 shell not perlaceous, but convex ; mouth slightly ob- 

 lique ; lips united ; base not produced : doubtful type, 

 stellaris. Mart. 164. f. 1553-4. calcar. En. Mhh. 451. f. 2. 

 CIDABIS Sw. Perlaceous ; turbinate ; generally smooth ; 

 the base not produced ; the inner lip not concave ; 

 always imperforate ; aperture round, but oblique ; 

 operculum very thick : representing Cattiostomus. 

 sarmaticus. Mart. 179. pethiolatus. Mart. 183. f. 



f. 1777, 1778. 1826. 



smaragdus. En. M. 448. f. 3. pictus Sw. En. Meth. 448. 

 E.coronatus. Sw. Chem. 165. f.5. 



f. 1585, 1586. ater Sw.* Sow. Gen. f. 7. 



SUB-FAM. TROCHIN^E. Trochus, or Top. 



Shell trochiform; the body-whorl more or less wide, 

 and flattened beneath; the spire conical or pyramidical; 

 aperture oval, wider than it is high ; operculum horny, f 



CANTHOBBIS. Operculum shelly; aperture very oblique, 

 broad, and narrow ; the basal whorl much flattened ; 

 pillar, in the typical examples, twisted : representing 

 Cerithium. 



Tubicanthus Sw. Turbinate; aperture oval, effuse; 

 very oblique; inner lip broad, concave, spreading, 

 united to the outer lip; base of the pillar simple, 

 blended with the circumference of the aperture.:): 

 rugosus. Mart. 180. f. Tuber. Mart. 165. f. 1373. 



17821785. Cookii. Ib. 163. f. 1540. 



caelatus. Ib. 162. f. 1536. 1 imbricatus. Id. 162. f. 1531. 



Canthorbis Sw. Suns. Nearly disk-shaped : spire but 

 slightly raised ; the margin of the body-whorl flat- 

 tened, and serrated with flat spines ; inner lip united 

 to the outer ; pillar and aperture as in the last. 

 C. imperialis. Mart. 173. f. 1714. 



* Is this the Turbo iugvbris ? Zool. Journ. v. 345. 



t Except in the first genus, which connects this sub-family and the 

 SenectirHE, and in T. Niloticus (as it is said), which connects Canthorbit 

 with Trochtts, 



$ Connected to Cidari by C. rugotus. 



