m8 PALEOZOIC FISHES OF NORTH AMERICA. 
In the paper read before the National Institute in 1857 on the Fossil 
Fishes of the Devonian Rocks of Ohio the following species were described : 
DEVONIAN FISHES. 
Macropetalichthys Manni, Newb. Macheracanthus peracutus, Newb. 
Macropetalichthys Sullivanti, Newb. Macheracanthus sulcatus, Newb. 
Onychodus Hopkinsii, Newb. Oracanthus fragilis, Newb. 
Onychodus sigmoides, Newb. Oracanthus granulatus, Newb. 
Psammodus antiquus, Newb. Oracanthus multiseriatus, Newb. 
Macheracanthus major, Newb. Oracanthus abbreviatus, Newb. 
Of these, Macropetalichthys Manni is perhaps only the young or a sexual 
variety of M. Sullivanti. Onychodus Hopkinsii is erroneously included in the 
list. as it is confined to the Chemung rocks, and will be noticed further on. 
Of the species of Oracanthus enumerated, perhaps none belong to the same 
genus with its type, Oracanthus Milleri of Agassiz, but they are more likely 
to prove to be some of the singularly varied spine-plates of Acantholepis. 
Combining all the notices of the fossil fishes of the Corniferous lime- 
stone published up to the present time, we have the following lists of species: 
ELASMOBRANCHS. 
Macheracanthus major, Newh. Oracanthus (?) fragilis, Newb. 
Macheracanthus sulcatus, Newb. Oracanthus (?) abbreviatus, Newb. 
Macheracanthus peracutus, Newb. Oracanthus (2) granulatus, Newb. 
Rhynchodus frangens, Newb. Psammodus antiquus, Newb. 
Rhynchodus secans, Newb. Cyrtacanthus dentatus, Newb. 
Rhynchodus crassus, Newb. 
GANOIDS. 
Macropetalichthys Sullivanti, Newb. Acanthaspis armatus, Newb. 
Macropetalichthys Manni, Newb. Acantholepis pustulosus, Newb. 
Macropetalichthys rapheidolabis, N. & O. Liognathus spatulatus, Newb. 
Onychodus sigmoides, Newb. Coccosteus occidentalis, Newb. 
Asterosteus stenocezhalus, Newb. 
Of the species mentioned in the above list those of the genus Machara- 
canthus ave the pectoral spines of Sharks, of which we have no other known 
remains. They are not uncommon in the Corniferous limestone of Canada, 
New York, and Ohio. The largest are sometimes a foot and a half in length, 
are composed of extremely dense tissue covered with polished enamel, and 
are sharp at the point and on the edges; the surface slopes from a central 
ridge to the margin on either side, and this slope is concave like those of a 
bayonet, apparently for the same reason, viz, to gain the greatest strength 
