214 GEOLOGY OF OHIO. 



the mouth of Black River, and at the mouth of the Vermilion. In the 

 former locality it is brought up in a fold of the strata to which allusion 

 has already been made. About fifty feet of the extreme summit of the 

 formation are here exposed, consisting of bands of black bituminous 

 shale, interstratified with gray shale and thin sheets of micaceous, pearly 

 sardstone. In the valley of the Huron, as generally farther south, it is 

 a nearly homogeneous black shale. Although showing such limited ex- 

 posures in the limits of Lorain county, the Huron shale has furnished 

 some of the most interesting and extraordinary fossils that have ever 

 been discovered. These are chiefly the remains of gigantic fishes, sim- 

 ilar in character to some of those described by Hugh Miller, but very 

 much larger. Most of the specimens obtained are referable to a single 

 species of the genus Dinichthys, which will be found fully described in 

 the palseontological portion of this report. The remains of Dinichthys 

 were first found by the Rev. H. Hertzer in calcareous concretions at the 

 base of the Huron shale, near Delaware, Ohio, and the species to which 

 they belong — named in honor of the discoverer — is figured and described 

 in Vol. I., Part II., p. 316, plates 30 and 31. Subsequently Mr. J. Terrell, of 

 Sheffield, and Prof. G. N. Allen, of Oberlin, found on the lake beach, west 

 of Avon Point, rolled fragments of large bones, which I recognized as 

 portions of the great dorsal shield of Dinichthys. The finding of these 

 specimens prompted a search for the bones in place in the cliff of Huron 

 shale from which they had evidently been washed out. This search was 

 rewarded with very interesting results. Prof. Allen obtained by exca- 

 vating the rock a complete dorsal shield some sixteen inches in diame- 

 ter ; and later, in company with Mr. G. K. Gilbert, a supra-scapular and 

 a large pre-maxillary tooth. But the most interesting specimens found 

 in this locality have rewarded the laborious and intelligent search of Mr. 

 J. Terrell, the proprietor of the Lake Breeze House, situated in the imme- 

 diate vicinity of the outcrop of the fish-bearing stratum. His first im- 

 portant discoveries were those of an entire dorsal plate and the posterior 

 half of a cranium, both of which are figured on plates 32 and 33 of our 

 first volume. Unfortunately, these speciments were destroyed in the 

 burning of Ely's block in Elyria. Their loss has, however, been more 

 than made good by Mr. Terrell, who has since discovered nearly the en- 

 tire bony structure of an individual of gigantic dimensions, of which a 

 more detailed description will be found in Part II. of this volume. This 

 proves to be a distinct species from that found at Delaware at the base of 

 the formation. The latter has a row of conical teeth on the edge of the 

 maxillary, and a corresponding row with which these interlocked in the 

 middle of the mandible, while in the Sheffield species, to which I have 



