FISHES OF THE DEVONIAN AGE. 29 
with the least material. It is an important fact that spines belonging to 
the genus Macheracanthus and possibly to the species MZ. major have been 
found in the Devonian limestones of Bohemia and in the Hartz Mountains, 
and are described by Barrande’ under the name of Ctenacanthus Dohemicus. 
The teeth to which I have given the name of Rhynchodus constitute a 
remarkable and interesting element in the fish fauna of the Corniferous lime- 
stone. There can be no reasonable doubt that they belonged to Chimeroids, 
and as they are numerous and exhibit considerable diversity of structure, 
they show that this group of fishes, now almost extinct, had its golden age 
far back in geological time. In some cases four teeth with pointed and 
‘upturned extremities formed a beak not unlike that of turtles and some 
birds; a structure that suggested the name given to the genus. In the 
largest species, R. frangens, which was much like and nearly as large as 
Chimera Townsendii, from the Jurassic, the upper edge formed a broad trit- 
urating surface. In another species, 2. secans, the edges were sharp, and 
played on each other precisely as did the dental plates of Dinichthys Terrelli. 
In one specimen which I have four are lying together approximately in 
their original positions. I have sometimes called these beak-teeth mandibu- 
lar, from their resemblance to the mandibles of birds, though aware that only 
half of them belonged to the lower jaw. 
Psammodus antiquus is notable, because, so far as known, it is the 
pioneer of the great group of pavement-toothed sharks of the Carboniferous 
age. 
The very peculiar spine, which I have called Cyrtacanthus, will proba- 
bly be found to be only one branch of a fork, and perhaps not generically 
distinct from Agassiz’s Cladacanthus; but if so, it will be the first Devonian 
species known, all others being of Carboniferous age. 
FISH BEDS OF THE CORNIFEROUS LIMESTONE. 
In the report of the Geological Survey of Ohio I have referred to two 
genuine fish beds in the Corniferous limestone of Ohio and Indiana.  Al- 
though they have furnished no complete fishes and few entire plates or teeth, 
they are of special importance, as they give us a better view of the fish life 
1Dr. E. Kayser, Die Fauna der iiltesten Devon-Ablagerungen des Harzes, Abhandl. Geol. Special- 
karte preuss., etc., 1878, vol. 2, Heft 4, p.3; Atlas, pl. 35, fig. 12. 
