170 TJie American Geologist. March, 1893 
speaks of five but figures six in (\ dccipieuH and they appear to 
vary from three to eight in different species. They are shown in 
the smaller figure (2) which is a view of the inner front edge of 
the mandible fortunately exposed on the very edge of the slab of 
shale and carrying the three bases of the syraphysial teeth with 
great distinctness. 
It would be useless here to enter on a discussion of the mode of 
using this peculiar dentition, unparalleled in the animal king- 
dom and onh' approached b}" that of Ottychodus and Diplognathus 
(and perhaps LiognatJius). The vertical row of teeth on the edge of 
the jaw led H. Miller to his conclusion that Coccostens united the 
dentition of a beetle or some similar invertebrate to the general 
structure of a vertebrate animal. This conclusion was the more 
pardonable because in his earh' specimens the teeth on the ramus 
of the jaw were missing. Subsequent discoveries led the illus- 
trious Scotchman to modif}', though scarcely to abandon, his first 
conclusion and to leave the structure of this anomalous mouth as 
a puzzle to his successors, which it remains to this da}'. 
It is just possible, though I am not aware that any specimen 
yet found bears out the supposition, that the two mandibles of 
Coccosteus did not close on each other so as to form a sutural 
union. In fact the presence of these sj'mphysial teeth almost 
renders this structure necessary. "We now know that in some 
kindred forms, such as Biuichthys, there were iutermandibular 
teeth which met and fitted against similar intermaxillarj' teeth in 
the upper jaw. If some similar arrangement existed in Coccosteus 
holding the two rami assunder at a small distance, opportunit}' 
would be afforded for the employment of the projecting sym- 
phj'sial teeth. The small size of all the previoush' known species 
may account for the non-discovery of such a plate even if it ex- 
isted. 
It may be that the tooth-bearing bone of Onychoclus lends some 
countenance to this suggestion but failing its actual production 
we can only at present speculate on the possibilities in the case of 
Coccosteus. Whatever may be the ultimate solution of this 
anatomical enigma it seems impossible that the symphysis of 
Coccosteus can have been a close one. 
For this new species is proposed the name of Coccosteus 
Cuyahoga, connecting it with the region in which it was discov- 
ered bv Dr. Clark. 
