FISHES OF THE CARBONIFEROUS SYSTEM. 1333 
occur at the angles of the mouth. This specimen is in the Geological 
Museum of Columbia College, New York. 
In the Waverly, on Oil Creek, Pennsylvania, Mr. G. K. Gilbert, found 
slabs of sandstone covered with the spines of Ctenacanthus triangularis, N. ; 
a dozen or more lying within an area of two square feet. As only two 
could have been worn by one fish, their accumulation in such numbers is 
not easy of explanation. . 
The Cleveland shale, through northern Ohio, is a black carbonaceous 
mass, twenty to sixty feet in thickness. It there rests upon the argillaceous 
Erie shale, which at Cleveland is several hundred feet in thickness, but 
which thins out toward the west; in Lorain and Huron Counties it is some- 
times wanting, letting the Cleveland shale down near to or upon the Huron 
shale, from which it can scarcely be distinguished by its lithologic char- 
acters. Over a large area, however, it is very distinct, and it is the source 
of the petroleum and gas of Grafton and Liverpool. It has also become 
celebrated for its fossil fishes. It is relatively barren of fossils, but, as in 
many other Carboniferous bituminous shales, at most localities the rhom- 
boidal scales of Palzeoniscoid fishes can be detected ; these are highly pol- 
ished, plain or ornamented, and somewhat abundant, but the fishes which 
bore them have never been found entire, and remain undescribed. 
At Bedford, Ohio, the surfaces of the layers of the shale are sometimes 
covered with Conodonts, of which thousands occur on a square foot. They 
exhibit considerable variety in structure and dimensions, but nothing what- 
ever is found with them which can explain their origin. Whether they are 
the teeth of Cyclostomous fishes, shell-less mollusks, or Annelids, remains 
undecided, but I know of no other locality where they are anything like as 
abundant as here. They occur in millions, and possibly careful study would 
reveal their history. In this locality I also obtained small teeth of Poly- 
rhizodus and Orodus (P. modestus, N., and O. elegantulus, N.). 
At Cleveland, the Cleveland shale forms a part of the hills which border 
the Cuyahoga Valley at its mouth, and is the surface rock in the cemetery 
where President Garfield is buried. From this region Mr. Frank Wagner, 
of Cleveland, has obtained a large number of bones and plates of Dinichthys 
Terrelli and one splendid and as yet unique tooth of a species of Ctenodus, 
