252 PALEONTOLOGY OF ILLINOIS. 



coronal region is sharply defined by a delicate sulcation in the angle 

 extending laterally from the median notch ; in the angles between the 

 median and the strong lateral cusps arise a delicate rudimentary dent- 

 icle on either side, but which are generally obsolete, possibly in conse- 

 quence of abrasion. The coronal cusps are apparently smooth ; however, 

 in some examples a few faint vertical stripe or thread like lines are dis- 

 cernible, the surface in all cases highly polished ; the basal region is 

 more or less roughened, with here and there large punctre or foramena. 



The teeth here mentioned bear intimate relations to the form from the 

 Kinderhook beds of the Lower Carboniferous, which we have referred 

 to the genus Pristicladodus of McCoy. This resemblance is strongly 

 marked in the general outline of the base and position of the coronal 

 cusps. But the absence of the deep median slit in the posterior margin 

 of the base, the confluent antero-iuferior basal prominence, and the 

 sharp definition therefrom in the lateral portions of the coronal region, 

 constitute an assemblage of features which seem to preclude their refer- 

 ence to that group. 



Dedicated in grateful and filial remembrance. 



Position and loeality : Magnesian beds of the middle Devonian ; 

 Waterloo, Iowa. 



Genus BATHYOHEILODUS, St. J. and W. 



Bathycheilodus McIsaacsii, St. J. and W. 



PI. I, Figs. 12, 13. 



Teeth minute, robust, symmetrical. Base laterally elongated, sub- 

 elliptical in outline, gently sinuose in front, and margined by a relatively 

 deep ridge which extends two-thirds the distance across the base, pro- 

 duced downward and outward, defining the moderately excavated infe- 

 rior surface, which is posteriorly beveled, posterior margin broadly 

 arched, lateral extremities sharply rounded and more or less produced, 

 postero- superior surface moderately convex and traversed by a narrow 

 central ridge nearly as extensive as the lateral diameter and direct, 

 sharply bevelled to the margin behind, surfaces more or less roughened. 

 Crown well-defined from the base, gently constricted in front and late- 

 rally, posteriorly sloping into the basal surface, and consisting of a 

 prominent ridge which is produced into a strong, rapidly tapering, 

 anteriorly compressed and posteriorly rounded median cone, with well- 

 defined cutting edges, flanked by a pair of nearly equally strong, 

 slightly diverging and recurved lateral denticles of similar shape, with 

 a minute intermediate denticle in the angles between the lateral cones 

 and the erect median cusp ; the outer coronal face is ornamented with a 



