2t) TRANSACTIONS OF THE [nOY. 9, 



whicli seem Lo have contributed most of tlie carbonaceous mat- 

 ter — in 1867 the Eev. Henry Hcrtzer found in calcareous concre- 

 tions near the base of the formation, at Dehiware, Ohio, some 

 hii'ge bones, M'hich were submitted to me, and subsequently de- 

 scribed in the Report of the Geological Survey of Ohio, with the 

 name of Dinicldliys Hertzeri. 



A few years later, Mr. Jay Terrell, who resided on the 

 shore of Lake Erie, where it is formed of the Huron Shale, fcnind 

 on the beach some rolled fragments of silicified bones, which 

 were sent to me in Cleveland, and identified as belonging to 

 Dinicldliys. 



Subsequently nearly the entire bony structure of this fish was 

 obtained by Mr. Terrell from the cliffs along the lake, and the 

 valleys of Black and Vermillion Rivers. These bones were 

 found torejoresent a distinct species of Dinichthys, to which the 

 name of the discoverer was given. And this also was described 

 in the Ohio Geological Report. 



Both the fishes mentioned were Placoderms, closely allied in 

 structure to Coccosteus, but very much larger, having a length of 

 fifteen or eighteen feet, while Coccosteus was only as many inches 

 m length. 



Later, the remains of two smaller species of Dinichthys were 

 found by Mr. Terrell, to .which the names of D. minor and D. 

 corrugahis were given. 



During the last summer, still another species, intermediate in 

 size between those already mentioned, Avas found by Dr. Gould, 

 of Berea, Ohio, in the cliffs bordering Rocky River, a few miles 

 west of Cleveland. Of this species the cranium is one foot in 

 length, the dorsal shield seven inches in diameter, and nearly 

 circular, the dentition, like that of D. Terrelli, consisting of 

 plates with cutting edges, which played on each otlier like shears; 

 but the premaxillary teeth are broader and flatter than those of 

 the larger species, the mandible narrower and straighter, with a 

 relatively longer cutting edge. 



The most interesting feature in this fish, however, consisted 

 in the great size of the eye, which was surrounded by a series of 

 sclerotic plates, like those of Ichthyoscmrus and the rapto- 

 rial birds. The circle formed by these plates was about four 

 inches in diameter. 



The discovery has latety been made by Prof, von" Koenen, 

 of Gottingeii, Germany, that in Coccosteus the eye was also 

 surrounded by a bony ring; and this affords another point of re- 

 semblance between these genera. 



This lately discovered species of Dinichthys was named D. 

 Gouldii, in honor of the finder, and it is described in the Comptes 

 Rendus of the late Geological Consrress at Berlin. 



