EASTMAN: CARBONIFEROUS SHARKS. 61 
Now, with respect to inrollment or coiling, we need only repeat that 
this character pervades numerous sharks, both those with piercing and 
those with crushing teeth. Indeed, some forms are known, such as 
Cochliodus, Psephodus, etc., which have posterior dental plates adapted 
for crushing, and feebly prehensile symphysial teeth (e. g., “ Helodus 
coxanus”’ Newberry). In Campodus the anterior series are only mod- 
erately arched, and the individual teeth scarcely override one another. 
But in Edestus, Campyloprion, and Helicoprion, not only is the coiling 
carried to a remarkable degree, but the teeth are angulated so that their 
bases either override or ensheathe one another. 
Respecting the disproportionate enlargement of the symphysial as 
compared with adjacent antero-lateral series, this condition appears to 
have been peculiar to Palzeozoic Cestracionts. We can almost certainly 
predicate its existence in Orodus, owing to the close similarity of its 
teeth to those of Campodus. And although the lateral dentition of 
Protodus, Edestus, Campyloprion, and Helicoprion has not yet been 
identified as such, nevertheless it follows from our interpretation of this 
class of remains that transverse rows of smaller teeth were present along 
the sides of each ramus of the Jaws. An understanding of Campodus 
having once enlightened us as to the disparity between the symphysial 
and lateral series of early Cestracionts, we are enabled to avoid the rather 
formidable conception of giant sharks in the Carboniferous, armed each 
with a mouthful of Edestus-like or completely coiled spirals, since there 
is no evidence to show that Edestus, Campyloprion, or Helicoprion pos- 
sessed more than one series, and this is to be relegated to the median 
line in front. Absence of marks of wear in the symphysial teeth of the 
three last-named genera, together with the difficulty of accommodating 
a paired series larger than that of Campodus in the upper jaw, favor 
the hypothesis that each individual possessed but a single arch, which 
was located presumably in the lower jaw. Although corresponding in 
position to the intermandibular arch of Onychodus, and to the pre- 
symphysial bone of Saurodon and Saurocephalus, it is obvious that no 
homology exists, as has already been shown by Newberry and others 
in commenting on Miss Hitchcock’s interpretation.} 
That the office of the symphysial dentition of Campodus was chiefly 
1 Ann. N. Y., Acad. Sci., Vol. IV. (1888), p. 118. Since the discovery of Heli- 
coprion by Karpinsky and its reference by him to the snout region of an Elasmo- 
branch, Jaekel has sought to revive Miss Hitchcock’s original interpretation of 
Edestus, regarding these structures “als Stossorgane, die aus dem Unterkiefer 
vorgestreckt waren.” Zeitschr. deutsch. geol. Ges., Vol. LI., 1899, p. 297. 
