98 HAY—VERTEBRATES OF CARBONIFEROUS AGE. [March 16, 
the midline of the base, on its posterior edge and directed backward, 
isa tubercle about 2mm. long. There is no indication of any 
button. The plane of the main cusps makes an obtuse angle poste- 
riorly with the plane of the lower surface of the base—that is, the 
main cusps project forward very distinctly. This species bears some 
resemblance to D. compressus (Newb.), but a close comparison 
with the descriptions and figures of that species makes it evident 
that it is not the same. Newberry’s species had all the denticles, 
even the median one, distinctly crenulated. The base of D. Jucast 
is evidently of a different pattern. Newberry regarded D. com- 
pressus as being closely related to D. /atus, but concluded that it 
possessed a smaller base, the dimensions being three lines long by 
two and one-half wide. O. St. John describes and figures the species 
(Final Report U. S. Geol. Survey Nebraska, 1872, p. 240, Pl. iv, 
Figs. 19", 19”). The base is shown to be narrower than long and 
to have an obtuse tubercle projecting downward anteriorly. The 
base of D. Zucasz is broader than long and possesses no such tubercle. 
The iron-stone nodule which furnishes the mold of this tooth 
bears the United States National Museum’s catalogue No. 4338 and 
also Prof. Cope’s symbol, F, 3, it having evidently been in his 
hands as a part of the Lacoe collection which he described. How- 
ever, it was not named by Prof. Cope. It is from the coal-measures 
of Mazon creek, Illinois. 
This species is named in honor of Mr. Frederick A. Lucas, Cura- 
tor of the Department of Comparative Anatomy, United States 
National Museum. 
CLADODUS GIRTYI, sp. nov. 
This species, which appears to be distinct from any hitherto de- 
scribed, was collected in the coal-measure deposits of Colorado 
by Dr. George H. Girty, of the United 
States Geological Survey, and it is named 
in his honor. It is represented by a single 
tooth. 
This consists of the base, a large median 
cusp and two smaller cusps on each side of 
the median one. Of the lateral cusps, the 
one on each side next to the main cusp is 
missing, but the size of these may be in- 
ferred from the size of the stumps remaining. ‘They couid hardly 
have been much smaller than the outside cusps. The base has a 
Fic. 2. Cladodus girtyi. 
