EASTMAN: CARBONIFEROUS SHARKS. 63 
the median series, it is considered remarkable that the apices themselves, 
which are sharp-edged and non-blunted, should be comparatively unworn. 
Biting as they did between the inner faces of the paired series of the 
opposite jaw, they would have become very obtuse had the creature’s 
fare consisted of hard-shelled prey, such as mollusks or echinoderms. 
This leads to the inference that Campodus and its congeners were 
sharks which subsisted chiefly on vegetation which flourished in the 
Carboniferous lagoons, or else upon soft animal prey. 
The coronal eminences of the median series in Campodus rise verti- 
cally above the rest of the tooth in the middle line, and are but slightly 
compressed from side to side. ‘The anterior and posterior edges are 
prominent, and although faint wrinkles occasionally appear, the edges 
are not serrated, in which respect they differ from Edestus and more 
specialized forms. In two other directions is Campodus less specialized 
than the Edestus-type: the symphysial teeth are, in their entirety, but 
little laterally compressed; and, secondly, although their crowns are 
inclined forward at a steep angle, they do not override one another, and 
their roots are not produced. 
Antero-lateral series. — We come now to a consideration of perhaps 
the most important feature displayed by the Kansas example, and that 
is the natural association of the symphysial with three of the antero- 
lateral series belonging to either side of the jaw. If, after all that has 
been said, any doubt remained whether the principal series were truly 
median and anterior in position, it would be dispelled by a mere inspec- 
tion of the smaller associated series. It is evident at a glance that the 
latter are scarcely at all displaced with reference to the median series, 
except in so far as the cartilaginous rami of the lower jaw have been 
pressed together prior to fossilization, and hence partly close over the 
median series behind. The continuity of the calcified cartilage, which 
supports not only the median but also the antero-lateral series on either 
side, positively identifies this as the symphysial region. Let the paired 
antero-lateral series with their supporting cartilage be imagined as 
opened out horizontally on either hand so as to include about the same 
angle between them as the jaws of Cestracion, and let these series 
be continued behind by 18 or more transverse rows of lateral teeth, 
we shall then have an adequate presentment of the lower dentition of 
Campodus. 
The antero-lateral series on the right-hand side of the symphysial are 
more perfectly preserved than those on the left, and are identical in all 
respects with the teeth occupying a corresponding position in the splendid 
