102 PAL/EONTOLOGY OF ILLINOIS. 



Genus SANDALODUS, N. and W. 



Gen. Char. — Teeth of medium or large size, thick and strong, 

 sub-triangular or club-shaped in outline, with one and some- 

 times two pointed extremities; generally somewhat twisted, 

 slightly arched longitudinally, strongly so transversely; enam- 

 eled surface firmly and uniformly punctate; base deeply con- 

 cave both ways, curves following those of the surface of the 

 crown ; toward the narrower end, in some species, one or two 

 obtuse ridges running obliquely over the tooth, as in Cocliliodus. 



In many respects these teeth show a resemblance to those of Deltodus and 

 Cocliliodus, but differ from them in their narrower, straighter forms and in 

 wanting, as a general rule, the ridges and furrows which are such conspicuous 

 characters in these genera. It is probable that with these elongated triangular 

 teeth there were associated others of different form, as we know was the case 

 in all or nearly all of the allied genera. If so, they are doubtless represented 

 among the many hundreds of placoid teeth which have been taken from the 

 beds where these were found. Whether any such exist in the collection, we 

 can, of course, only conjecture, as the cartilaginous supports upon which they 

 once rested have entirely decomposed, and the teeth, separated from their con- 

 nections, scattered broadcast over the sea bottom. The tooth which we have 

 called Cocliliodus? crassus, (plate VIII, figs. 2 and 2a,) with a form quite un. 

 like any heretofore described, has the same dense and massive structure and 

 precisely similar surface with the larger species of Sandalodus ($. grandis), 

 which is also found in the same stratum, at the same locality — near Warsaw. 

 It is therefore at least possible that this beautiful specimen is one of the short 

 intermediate teeth of that genus. 



Sandalodus parvulus, N. and W. 



PL X, Fig. 1. 



Teeth small, thin, irregularly oblong in outline, obliquely 

 truncated at the narrower end, broader extremity pointed, 

 triturating surface slightly arched longitudinally, strongly so 

 transversely, finely and uniformly punctate throughout, under 

 surface strongly concave, smooth. 



