50 PAL.T.ONTOLOGY OF OHIO. 



rudimentary one at tlie base of the central cone), of M'hicli the inner pair 

 are sli^^htly higher than the outer ones ; surface of both central and 

 lateral cones very sti'ongly striated. 



This beautiful species strongly resembles in general appearance G. acu- 

 tus and C miralnlis^ of Agassiz (described in the Pousons Fossiles, Tome 

 ITL, 2^1>- 197, 199, P/«/6 22, i^'(75..9, 13-21), but differs from both in 

 having the internal pair of secondary cones as large as, or larger tlian, the 

 outer pair. In this respect it is unlike any other species known to me, ex- 

 cept C. Jlertzeri^ described on another page. 



This remarkable tooth was found by Dr. C. Rominger, in a calcareous 

 sandstone of Waverly age, at Battle Creek, Michigan. To his kindness 

 I am indebted for an opportunity of examining it; a courtesy which I take 

 pleasure in acknowledging by attaching his name to it. 



It has not been possible to have drawings made of it in time for puljli- 

 cation in this volume. 



POLYRHTZODUS M0DE3TUS (ll. Sp.). 

 Plate LVin., Figs. 10, 10 a. 



Teeth small, largest half an inch in breadth and height. Crown sur- 

 face 2 lines wide, much depressed, terminating posteriorly in an acute 

 edge ; root broad, and divided below into five or six flattened radicles. 



Of this little tooth only one complete specimen has yet been found. 

 This, with fragments of others, give fairly well the character of the species 

 and show it to be distinct from any other yet described. 



In the Report of the Geological Survey of Illinois, Vol. II., several spe- 

 cies of Polyrhisodus 2a'e. figured and described, all indeed, with one ex- 

 ception, that have been heretofore met with in this country. By com- 

 paring the figure now given with those in the Report referred to, it will 

 be seen at a glance that the tootli before us is so different that no detailed 

 comparisons are rec[uired. 



Formation and Locality: Cleveland shale, Bedford, Cuyahoga County, Ohio. 



Orodus variabilis (n. sp.). 



Plate LVIIL, Figs. 11, 11 7(. 



Teeth of various forms and dimensions, the largest 15 lines in 

 breadth, 5 lines in height and 2| lines in thickness ; the crown on 

 the posterior face forming half the height of the tooth, rising in the 



