356 PALAEONTOLOGY OF ILLINOIS. 



terior face; posterior face elliptical in outline, basal enamel 

 folds 5-6, broad and strong ; root relatively short and thin, on 

 posterior face two-thirds the hight of the crown, in breadth 

 two-thirds that of the crown, sides nearly straight, bottom 

 arched and somewhat three-lobed, strongly bevelled off so as 

 to form a blunt edge on the anterior and longer side. 



In general aspect this tooth resembles most P. linguifer, N. and W., from the 

 Chester limestone, but it is thinner, and has a much shorter root, of which the 

 lower edge is characteristically bevelled. There is no other species for which 

 it is likely to be mistaken. 



Formation and locality : Keokuk limestone; Otter creek, Jersey countyi 

 Illinois. 



GENUS ANTLIODUS. 

 ANTLIODUS SARCULULUS, N. and W. 



PI. ii, fig. 8, 8(7, 8&. 



TOOTH small, oval in outline, thin ; root entirely obsolete ; 

 upper surface polished and obscurely striated ; anterior border 

 raised into a sharp cutting edge, roughened but scarcely ser- 

 rated by the extremities of the calcigerous tubes ; posterior 

 margin bordered by about three imbricating enamel folds, 



*/ t_j / 



which form a deep bow-shaped arch ; anterior face vertical, 

 less than half as high as the antero-posterior diameter of the 

 tooth, terminating in an arched cutting edge above, below by 

 two or three very narrow imbricating folds, surface polished 

 but obliquely punctate ; under surface sub-triangular in out- 

 line, bony, posterior portion roughened. 



This is another of the small unguiform teeth which are so common in tlfe 

 Lower Carboniferons limestone of the Western States, and which form our 

 genus Antliodus. On comparing it with the species before described it will be 

 seen that while approaching closely in dimensions and general form to A. par- 

 vulus (vol. ii, p. 38, PI. vi, fig. 7, 7a, 76) and A. minutus (op. cit. p. 43, PI. iii, 

 figs. 3, 3a, 36,) it is specifically distinct. It is a little larger than either; is 

 without the rudimentary roots of A. pai-vulu*, less regularly oval in outline, and 



