346 TJie American Geologist. December, i899 
I wish to make some remarks on certain fossil reptiles of 
North America. 
In 1856 Dr. Leidy* described a new genus of dinosaurian 
reptiles from the Judith River beds of Montana, and this genus 
he called Deinodon, the single species being D. horridus. A 
more extended description with figures was published by Dr. 
Leidy f in i860. When these descriptions were written Dr. 
Leidy was in doubt whether all the teeth comprehended under 
the name which he gave belonged to a single species or even 
a single genus. Some of the teeth, represented by figures 21- 
34, plate IX, as cited, resemble those of Megalosaurus and are 
broadly elliptical in section, with two denticulated carinae, on 
opposite sides of the crown. Other teeth, represented by fig- 
ures 35-45, are somewhat U-shaped in section, with one nearly 
plane surface, corresponding to the top of the U, and this sur- 
face is bounded on each side by a denticulated carina. But 
none of these teeth was especially designated as types of the 
genus Deinodon. 
In 1866 Prof. Cope;]: in considering these teeth, restricted 
the genus Deinodon (spelled Dinodon, however) to the teeth 
represented by figures 35-45 of Dr. Leidy's plate. The Meg- 
alosaurus-like teeth, represented by figures 21-34, Prof. Cope 
regarded as belonging to his own genus Laslaps. In 1868 Dr. 
Leidy§ again took up the subject; and refusing to be bound by 
Prof. Cope's action, he retained Deinodon (with the orthogra- 
phy Dinodon) for the teeth of figures 21-34; while for the 
others he proposed the new generic name Aublysodon, the 
species being called A. mirandus. In the same year Prof. 
Cope, II replying to Dr. Leidy, defended his own procedure, but 
accepted Dr. Leidy's generic name Aublysodon on the ground 
that "Dinodon" had been preoccupied by Dumeril and Bibron 
for a genus of snakes. 
LTndoubtedly. Prof. Cope, being the first to distribute the 
materials of Dr. Leidy's composite species and genus, had 
entire right to assign the original name to such part thereof as 
he chose, and succeeding writers ought to have respected his 
*Proc. Acad. Nat. Sci. Phila., 1856, p. 72. 
tTrans. Amer. Philos. Soc, vol. XI, p. 144, pi. IX, figs, 21-48. 
JProc, Acad. Nat. Sci. Phila., 1866, p. 279. 
§Proc. Acad. Nat. Sci. Phila., 1868, p. 198. 
llAmer. Jour. Sci., [3], vol. XLVI, p. 415. 
