196 
PROCEEDINGS OF 
A fourth species, consisting of a portion of the superior jaw, has been found in 
the calcaire grossier, in the department of Orne. 
M. Cuvier has been able to satisfy himself that all these species are distinct front 
each other, as well as from the living species. 
The specimen before us bears the nearest comparison with the first of the above 
named species, but is sufficiently distinguished by the larger size, relative proportions, 
and number of teeth of the Appenine species. 
Description of D , Calvertensis. —In general outline, resembling other skulls of 
this genus. The head is proportionably narrower, and snout more elongated, than 
the Italian specimen with which I have compared it. The occipital and temporal 
ridges are strongly developed, indicating muscular strength, especially of the jaws. 
We find similar indications in the remains of the teeth, which have been large and 
robust. There are ten sockets remaining on the right side, with the teeth broken 
off at the rim. These organs approximate each other. The ten sockets include a 
line four and a half inches long. There has been about one and a half inches of 
the end of the snout broken off, which would afford room for two or three more 
teeth—making twelve or thirteen, in all, on each side. The pyramidal eminence, 
anterior to the posterior nares, on the palatine surface, is strongly pronounced. It 
terminates opposite the last tooth. The excavations or longitudinal grooves, on 
each side of the upper portion of this eminence, are unusually deep. The palatine 
surface is slightly convex transversely. Above, the head is narrower across the 
occipital ridges than other allied species, and narrower than the transverse diame» 
ter of the base of the skull. The ossa nasi are longer than broad, and convex. 
The atlas vertebra adheres to the occiput, above the condyles. It measures, across 
the transverse processes, five inches; transverse diameter, three inches; and the 
ring is about one inch thick. 
In the following admeasurements, one and a half inches must be considered as 
the length of the last portion of the extremity of the snout. 
Dimensions. —Total length of head, from the temporal crest to the presumed ex¬ 
tremity of the jaw, --------- 17 inches. 
From the anterior borders of the spiracles to the presumed ex¬ 
tremity of snout, - -- -- -- -- - 11.5 inches. 
Breadth of skull above, across the occipital crests, - - - 5 inches. 
Breadth at base, between the temporal bones, - 6.5 inches. 
Longest diameter of largest tooth at the socket, - - - 3^ tenths. 
The head of the Appenine species is one foot, ten inches, nine lines long, French 
measure. The spiracles are one foot nine inches, from the extremity of the snout. 
The accurate figures which accompany this description, will render further de¬ 
tails unnecessary. 
Geological Series: Middle tertiary of Maryland. 
Description of the Plates. 
Figure 1.—Basal view of the skull. 
Figure 2.—Superior view of the skull. 
Figure 3—Lateral view of the skull. 
Figure 4,—Occipital view of the skull. 
