1900. ] HAY—VERTEBRATES OF CARBONIFEROUS AGE. 99 
width (measured parallel with the jaw) of 15 mm., and a length 
(measured across the jaw) of 5 mm. The outline of this base 
is somewhat excavated in front beneath the central cusp, forming 
a sinus, and projects somewhat both forward and downward just 
below each first lateral cusp. The central cusp has a héight of 
12.5 mm., measured from the under side of the base; while the 
outer cusps, measured in the same way, have a height of 7 mm. 
The main cusp has, at the base, a width of 4.5 mm. and is of a 
lanceolate form. It has a sigmoid flexure, the profile being, just 
above the base, convex in front; just below the tip, concave in 
front. The outer lateral cusps are straight and rather stout in 
form. ‘The section of the main cusp is lenticular, or nearly semi- 
circular, the anterior outline being much less convex than the poste- 
rior. Theedgesare trenchant. The anterior face of the main cusp is 
ornamented by about a dozen sharp costz, separated by rounded 
grooves. Of these costz, the median ories run up three-fourths the 
way to the tip of the tooth. Those nearer the edges are succes- 
sively shorter. The posterior face of this cusp is similarly orna- 
mented. 
The lateral cusps have a hexagonal section, the sides of the 
hexagon being concave outwardly. Seen from the front, these 
cusps each present three sharp costz separated by broad rounded 
furrows. 
This species resembles in various respects certain other species. 
Cladodus gracilis N. and W., of the coal-measures of Indiana, has 
the median cusp marked by a few coarse, sharply-prominent striz, 
but these are said to be somewhat irregular. The lateral denticles 
are very long, slender, nearly cylindrical and coarsely striated. 
Cladodus intercostatus St. J. and W., of the upper Burlington 
deposits of Iowa and Illinois, also possesses certain resemblances. 
However, the postero-superior surface of the base of that species is 
said to be ‘‘surmounted near the posterior margin by a laterally 
elongated, narrow, roughened prominence, equal to about half the 
lateral diameter of the base’’; of this I find no indications in 
C. girtyi. The ornamentation of the cusps of the two species is 
also evidently much different. 
It might be supposed that the species here described is more 
likely to be identical with C. mortifer N. and W., a species of 
the coal-measures of Illinois, Indiana, Iowa, Nebraska and Kansas, 
But aside from other differences, €. mortifer is described and fig- 
