[ 69 ] 



V. — Observations on the Basilosaurus of Dr. Harlan (^Zeuglodon cetoides, 



Owen). 



By RICHARD OWEN, Esq., F.G.S., F.R.S. 



[Read January 9, 1839.] 



Plates VH., VIH., and IX. 



J.N the recent discussion on the Stonesfield fossil jaws, one of the arguments ad- 

 duced in support of the Saurian hypothesis of these jaws was founded on the pre- 

 sumed existence of a reptile possessing teeth with double fangs, this reptile being 

 the Basilosaurus of Dr. Harlan *. I refused to admit the validity of this argu- 

 ment until the teeth had been subjected to a re-examination, with an especial 

 view to their alleged mode of implantation, and I adduced as reasons for my objec- 

 tion, the instance of the Megatherium, in which the highest authority in Compara- 

 tive Anatomy had been deceived in regard to this very point of structure. (See 

 ante, p. 61.) But the appeal to the Basilosaurus had rendered it desirable to de- 

 termine, not only the actual mode of implantation, but also the general conditions 

 of the teeth of that interesting and problematical fossil, and I felt more especially 

 desirous to apply to them a test founded on the microscopic examination of their 

 intimate structure, which in many other cases I had found to afford very satis- 

 factory and unexpected results. The arrival of Dr. Harlan in this country with 

 some of the remains of the extinct animal in question, and the permission which 

 he has hberally granted me of having the sections of his valuable fossils made 

 which I required, have enabled me, much sooner than I could possibly have hoped, 

 to arrive at such conclusions, as to the nature of the Basilosaurus, as can be safely 

 founded on the dental characters ascertainable by this mode of investigation ; and 

 I now, in comphance with Dr. Harlan's request, proceed to recount the details of 

 this examination. 



The parts of the Basilosaurus, relating to the present subject, brought over by 

 Dr. Harlan, and now on the table, are two portions of bone belonging to the upper 

 jaw ; the larger one containing three teeth (PL VII.), the smaller one the sockets 

 of two others. 



The crowns of the teeth in the larger portion are more or less perfect, and are con- 

 tiguous to each other ; but they are placed rather obliquely, so that the inner surface 



* Medical a,ad Physical Researches, 8vo, 1835, pp. 337, 349. 



