196 PROCEEDINGS OF THE ACADEMY OF 



Notice of some extinct CETACEANS. 

 BY JOSEPH LEIDY, M. D. 



HOPLOCETDS OBESUS. 



Prof. F. S. Holmes, of Charleston, S. C, has recently submitted to my in- 

 spection a remarkable tooth and the fragment of another, which I recognize 

 as having belonged to an extinct genus of Cetaceans, characterized under the 

 name of Hoplocetus by Gervais, from similar teeth derived from the miocene 

 and pliocene formations of France. The tooth, indeed, bears a near resem- 

 blance to that of //. crassidens, represented in figure 10, plate xx, of Gervais' 

 Pal^ontologie Francaise, both in form and size, but is more curved, in this 

 respect resembling more the tooth of that represented in fig. 11 of the same 

 plate. Prof. Holmes' specimens were obtained from the post pliocene forma- 

 tion of Ashley River, in the vicinity of Charleston, S. C. 



The more complete tooth has the end of the fang and a good portion of the 

 crown broken away. The latter was worn away, leaving on the summit a 

 broad, flat, discoidal surface. The enamel, where it remains, forms a band 

 encircling about one-third of the crown, about three lines in depth, and one- 

 fourth of a line thick. It appears to have been rugose longitudinally. The 

 fang, a striking character in the teeth referred to Hoplocetus, is fusiform, re- 

 markably robust, and large in proportion to the crown. It is straight at the 

 bottom two-thirds, but curved towards the crown, so that this appears to be 

 obliquely implanted upon it. The interior of the fang is pervaded by a 

 narrow pulp cavity of irregular diameter, from the existence at its sides of 

 nodosities. The part constituting the technical neck of the tooth is feebly 

 constricted. The measurements of the specimen are as follows : 



Length in present condition in a straight line 44 lines. 



Estimated length of fang restored 52 " 



Greater diameter of fang 19 " 



Lesser " " 16^ '« 



Estimated diameter of crown at base 8 " 



The fang of this tooth appears to consist of an axis of dentine about equal 

 in diameter to the crown, and its great accession of bulk appears to be due to 

 the cemental layer. 



The second specimen consists of the fragment of a tooth devoid of crown. 

 The tooth has been of little greater bulk than the preceding, as the diameter 

 of the remaining portion of the fang is 20^ lines. 



Almost immediately after the reception of the above specimens, quite un- 

 expectedly' and purely coiucidentally, I received, among some other cetaceous 

 remains, another tooth, referable to Hoplocetus, from my friend, Prof. Wyman 

 of Cambridge. This specimen was derived from the miocene formation in 

 the vicinity of Richmond, Va. The tooth is much larger and straighter 

 throughout than the better preserved of the two preceding specimens, and 

 may perhaps belong to a different species, — a conjecture which is favored in 

 the fact that the tooth was also derived from a different geological for- 

 mation. 



The crown is worn off in a blunt manner or somewhat convex disk, about 

 9 lines in diameter, and is encircled by a more or less worn and broken band 

 of longitudinally rugose enamel, varying in depth from three to five lines, 

 and one-third of a line in thickness. The fang is broken at its end, and ex- 

 hibits- a long conical pulp cavity, large enough to introduce the end of the 

 middle finger for an inch or more. The fang in shape is fusiform, exceed- 

 ingly robust, straight, and somewhat quadrate. As in the other specimens, 

 it is composed of a dentinal axis near the diameter of the crown, enveloped 

 in a huge accumulation of cementum. The length of the specimen in a 

 straight line, in its present condition, is 55 lines. The fang in a restored 



[August* 



