68 Dr. Harlan on the Basilosaurus, Bfc. 



one at 100 feet, the other 150 feet in length, — the peculiar structure of the ribs, 

 the form and size of the humerus, all differ widely from those parts in any of the 

 known species of the Cetacea. I nevertheless take pleasure in acknowledging 

 that the accurate and laborious investigations, and inteUigent observations, made 

 by my friend Mr. Owen on these fossils, during the several days they remained 

 with him at the Royal College of Surgeons, have thrown new light on their struc- 

 ture and analogy. The remarks which we hope to elicit from him on the present 

 occasion, Avith the means he possesses to verify them, will no doubt enable the 

 Members to arrive at some final conclusions as to the true position which the 

 animal under discussion ought to occupy in the animal kingdom. 



I believe no one doubts that it is generically distinct, at least, from anything 

 fossil or recent hitherto discovered. 



I must now be indulged in a few observations on another extinct fossil animal, 

 which has occupied much attention. It is the portion of the snout of a Saurian, 

 said to be upwards of seventy feet in length, the head being only three or four 

 feet long. It was discovered some eight or ten years since by a beaver-trapper, 

 on or near the banks of the Yellowstone river, in the territory of Missouri, im- 

 bedded in a hard blue limestone rock. On my first examination of this specimen, 

 I was under the impression, that it belonged to the genus Ichthyosaurus, though 

 differing very materially from any species hitherto described ; the structure of the 

 teeth, mode of dentition, and the position of the anterior nares, led to this ana- 

 logy ; but the separate alveoli, and the form and position of the intermaxillary 

 bones, separate it from this genus. 



■ On my return from Europe in 1833, the memoir on this animal, which I had 

 offered through the Transactions of the American Philosophical Society, was just 

 passing the press ; I had therefore only time to add the following note : — 



" Since WTiting the foregoing essay, the author has enjoyed a more extensive 

 field of observation, in the numerous and magnificent collections of Europe, and 

 has satisfied himself, that the ' Missouri fossil ' must be considered as an ex- 

 tinct fossil and altogether new, characterized, more particularly in the fragment in 

 question, by the extreme length, breadth, and projection of the intermaxillary 

 bone, in which it presents a marked difference from any of the genus Ichthyo- 

 saurus, and approaches the Batrachian order." {Vide Transactions of the Ame- 

 rican Philosophical Society, 1833 ; and Medical and Physical Researches, p. 148.) 

 As the name under which this animal was originally described, must be changed, 

 I propose to designate it as the Batrachiosaurus Missouriensis. 



R. HARLAN. 



London, January 9, 1839. 



