108 IOWA GEOLOGICAL SURVEY 



Gladoclu8 prototypus Eastman. 



(Plate I, Fig. 18) 



1907. Cladodus prototypus C. R. Eastman, Mem. N. Y. State Mus. 10, p. 61, 

 pi. 1, tig. 15. 



Founded upon a single robust tooth of large size, the crown 

 consisting of a stout, erect median cone and five lateral denticles 

 on either side, not much compressed, and all delicately striated. 

 The outer pair of lateral denticles is much the largest, and nearly 

 circular in transverse section. The median cone is elliptical in 

 cross-section, slightly recurved, without sharp lateral edges, and 

 very broad across the base. Its total height, when complete, is 

 estimated to have been about 3 cm. 



The genera] appearance of the unique tooth answering to 

 the above description is suggestive of C. striatus Agassiz, from 

 the Lower Carboniferous limestone of Great Britain. The present 

 example differs from the latter species, however, in the less 

 compression of the crown, fewer lateral cones, and peculiar ar- 

 rangement of the coronal striae. As many as thirty-five fine, 

 parallel non-bifurcating striae are visible on the external face of 

 the principal cone, those of the middle portion running vertically, 

 and those along the sides curving gradually outwards and ter- 

 minating in a faint ridge along the lateral margin. The apices 

 of the median and nearly all of the lateral cones have unfortu- 

 nately been broken away in the type specimen, and the root like- 

 wise is wanting. The length of the base in its present condition 

 is 3.6 cm. Holotype preserved in American Museum of Natural 

 History, New York (ex James Hall Collection). 



Formation and locality. Columbus limestone (Ulsterian) ; 

 Columbus, Ohio. 



Cladodus monroei Eastman. 

 (Plate I, Fig. 17) 



1900. Cladodus monroei C. R. Eastman, Jonrn. Geol. 8, p. 36, text-fig. 2. 

 1907. Cladodus monroei C. R. Eastman, Mem. N. Y. State Mus. 10, p. 62, pi. 

 1, fig. 5. 



The holotype of this species is a small, imperfectly preserved 

 tooth found by Mr. Charles E. Monroe in the Hamilton lime- 

 stone of Milwaukee, Wisconsin. The median cone is robust, very 



