PART II. TROCHIN.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. M^h. 451. f. 2. 



CiDARis Sw. Perlaceous ; turbinate ; generally smooth ; 

 the base not produced; the inner hp not concave; 

 always imperforate ; aperture round, but oblique ; 

 operculum very thick : representing Calliostomus. 

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



f. 1777, 1778. 1826. 



smaragdus. En. M. 448. f. 3. pictus Sw. En. M^th. 448. 

 E.coronatus. S"?/;. Cheni. 165. f. 5. 



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



SuB-FAM. TROCHINiE. Trochus, or Top. 



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

 and flattened beneath; the spire conical or pyramidical; 

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



Canthorbis. Operculum shelly ; aperture very oblique, 

 broad, and narrow ; the basal whorl much flattened ; 

 pillar, in the typical examples, twisted : representing 

 Cerithium. 



Tuhicanthus Sw. Turbinate; aperture oval, effuse; 

 very oblique ; inner hp 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. 



1782—1785. Cookii. lb. 163. f. 1540. 



caelatus. lb. 162. f. 1536. 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 luoubris ? Zool. Jouni. v. 345. 



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

 Sencctini', and in T. Niloticus (as it is said), which connects Canthorbii 

 with Troc/ius. 



X Connected to Cidaris by C. rugosus. 



