74 



SPONDYLUS. 



(Plate VII. fig. 6.) 



Shell inequivalve, rough. Hinge liaving two re- 

 curved teeth with an intermediate hollow ; some- 

 times eared, (fig. 5.) One of the valves convex and 

 thick, the other flatter. 



The intermediate sinus contains a connecting 

 cartilage as in some other genera. The lower of 

 the two valves of this singular shell is, in many indi- 

 viduals of the first species, Gcedarop2is, produced 

 towards the apex into a projecting beak, one side of 

 which is excavated so as to leave a flat space per- 

 pendicular to the hinge. Through this the cartilage 

 is continued in a curvilinear direction to the very tip. 

 The appearance is that of an imperfect specimen 

 having one of the apices artificially mutilated. 

 The surface is always coarse and rough, tubercu- 

 lated or spinous, and more or less pectinated. 

 With the exception of the strong and well defined 

 teeth which are peculiar to this genus, and which 



