54 BIVALVES. — SPONDYLUS. 



above-mentioned tints, and the ramifications are left en- 

 tirely white. 



In some instances there is a compound of colouring, as 

 white and brown, purple and white, &c. which gives the 

 shell a pied or brindled appearance ; and in others (especi- 

 ally those which have a tendency to being foliated as well 

 as branched) the upper valve is of one colour, as purple or 

 brown, while the lower valve is perfectly white. 



The valves of the Spondyli are generally unequal, the 

 lower one protruding much beyond the other, and often 

 terminating in a curved and lengthened beak. 



The hinge is furnished with two recurved teeth, which 

 are very strong and articulate, and separated by a small 

 but deep hollow; the inner margin is mostly crenulate ; and 

 highly coloured with orange or purple. Some of this genus, 

 like the escallops, are surmounted with ears on each side of 

 the beaks; others, on the contrary, are perfectly earless. 



They are generally found adhering to rocks, corals, &c. 

 in groups more or less numerous, often forming large mass- 

 es, and sometimes attached to shells. They are to be 

 met with in the American, Indian, Mediterranean, and 

 other seas. 



SVO^DYLUS— Thorny Oyster. 



Division I. — Shell armed with spines or ramifications. 



Family 1. — Sharp spines. 

 Gsedaropus — Thorny red. Aurantius — Orange. 



Regius — Royal. Citrinus — Yellow. 



Histrix — Hedge-hog. 



Family 2 Having palmated or foliated ramifications. 



¥a\ms.tus—Pal7nated. Spathuliferus— Peerf. 



Ducalis — Ducal. 



