VERTEBRATES. 29 



spire with two flanking pinnacles, a resemblance which has suggested the name 

 given it. The relative length of the base is less than in any other described 

 species, unless in C. micropus, which, though smaller, more curved, and with 

 less developed lateral denticles, is otherwise not unlike it. 



Figure 14, anterior face and section of median cone, natural size. 



Formation and locality: Keokuk limestone, Warsaw and Nauvoo, Illinois. 



Cladodus grandis, N. and W. 



PI. 1, Figs. 15, 15a. 



Teeth very large and robust ; breadth 1 i times the height ; 

 base thick and flat, anterior border excavated by a broad sinus 

 beneath the median cone, and marked with numerous fine, 

 sharp, vertical carinas anterior to the bases of the lateral den- 

 ticles ; median cone robust, acute, somewhat flattened through- 

 out, especially on the anterior face, upper two-thirds with a 

 lenticular section and cutting edges, basal half of anterior sur- 

 face finely longitudinally striated, upper half smooth, two-thirds 

 of posterior surface marked with stronger vertical striae, which 

 converge to the base of the dorsum ; summit smooth ; lateral 

 denticles numerous (5-8 on either side) and very unequal in 

 size ; exterior pair one-fourth the length of the principal cone, 

 conical and strongly striated at base, compressed and smooth 

 at summit ; intermediate ones sub-equal, very small, striated. 



This is the largest tooth of the genus yet discovered, and must have formed 

 the armament of a fish of formidable dimensions and prowess. In one specimen 

 the principal cone, now somewhat mutilated, must have been 1J inches in length; 

 in another, nearly entire, the median cone is 1 inch, 1 line in length; the base 

 1 inch, 8 lines broad. 



From all species hithereto discovered this is readily distinguishable. Ap- 

 proaching, by its general aspect and fine striation, most nearly to C. Milleri, Ag., 

 it is widely separated from that species by the compressed form and trenchant 

 edges of the median cone and the greater number and marked inequality of the 

 lateral denticles. Of the species with which it is associated in the collection, 

 C.magnificus, Tuoniey, (if we have correctly identified that species), is most like 

 it in general aspect and nearly equals it in size; but in C. magnificvs the prin- 



