38 PALAEONTOLOGY OF ILLINOIS. 



Genus ANTLIODUS, N. and W. 



Antliodus mucronatus, N. and W. 



PI. II, Figs. 6, 6 a,6b. 



Teeth small, robust, broader than high, posterior crown face 

 lenticular in outline, with very sharp angles, concave vertically 

 and laterally, smooth or very finely striated vertically under 

 the lens; superior border regularly arched, finely crenulated; 

 basal folds about 5, upper one nearly equaling the lower four 

 in breadth, forming a narrow, prominent, bow-shaped ridge; 

 anterior surface equal in height to posterior, strongly arched 

 laterally, vertically concave below, arched above ; basal ridge 

 a sharp prominent angle, without distinct folds ; base arched 

 laterally, strongly concave vertically, smooth; root two-thirds 

 as wide as the crown, apparently divided into several radicles. 



A very distinct and neat species, characterized by its low, thick, and strongly 

 arched crown, terminating laterally in very acute depressed points. 



Figures 6, 6 a, 6 b, represent front and rear views, with profile, natural size. 

 Formation and locality: St. Louis limestone, Alton, Illinois. 



Antliodus parvulus, N. and W. 



PI. II, Figs. 1, 7 a. 



Teeth small, elliptical in outline, height two-thirds the 

 breadth; cutting edge regularly arched, crenulated; anterior 

 surface of crown just half the height of the tooth exclusive of 

 the rudimentary root, smooth and polished, except along the 

 upper border, where it is striated, terminating below in a bow 

 shaped coronal ridge ; posterior surface concave, higher than 

 anterior, smooth with the exception of the striae along the 

 cutting edge ; root nearly obsolete, existing only as a narrow 

 fringe below the central two-thirds of the crown. Height 4 

 lines ; breadth 6 lines. 





