FISHES OF THE DEVONIAN AGE 31 
A fish-bed not unlike this occurs in the Corniferous limestone at North 
Vernon, Ind. The two deposits correspond closely in geological position 
and character, and many of the fossils are the same in both, so that we 
must conclude they have had a similar history. Among the fossils of the 
Columbus fish bed there are thousands of the teeth of Onychodus, with frag- 
ments of the head plates of this genus and of Macropetalichthys ; the latter 
recognizable by their peculiar tuberculation. The spines of Machcracanthus 
and Acanthaspis also occur there, but by far the most numerous of the fos- 
sils contained in the deposit are the stud-like dermal ossicles of Selachians 
Of these most are plain, but some have the exposed surfaces ornamented 
with radiating ridges, like a scallop shell, and closely resemble those de- 
scribed by C. H. Pander! under the name of Celolepis and Nostolepis. Asso- 
ciated with these are numerous Elasmobranch teeth, generally of small size 
and showing considerable diversity of form, but most of them would prob- 
ably come into the genus Chomatodus of Agassiz. 
The abundance of the remains of Elasmobranch fishes in this deposit 
is surprising, considering their general scarcity in the Corniferous limestone, 
and indeed in all the Devonian rocks It should be said, however, that even 
here the relies of Sharks are, with the exception of the spines of Machcra- 
canthus, all small, and we find nothing which requires important qualifica- 
tion of the view advanced in the Paleontology of Ohio, viz, that ‘in the 
Devonian seas the Elasmobranchs were comparatively few and small, and 
they were far surpassed in numbers and in size by the scaled and plated 
Ganoids, which constituted the summit of the zoologic series and the ruling 
dynasty at that age of the world.” 
The fish-beds described above deserve more careful consideration than 
they have yet received, and it is to be hoped that some one who is favora- 
bly located will make them the objects of careful and prolonged study. 
In no other way can the immense mass of animal remains they include be 
properly investigated, and it is quite certain that the results would justify 
the devotion of considerable time to the task. Both the deposits are verita- 
ble cemeteries; they extend over considerable areas and are very accessi- 
ble. Probably all the fishes that lived in the waters from which the Cor- 
! Monographie der foss. Fische des silurischen Systems, p. 65, Pl. 4, Fig. 13. 
