8 MEMOIR ON MOSASAURUS 



the osseous support of the tooth, the cavity in which was contained the successional 

 or secondary tooth.* From the size of the tooth and estimated thickness of the 

 maxilla, it must have characterized one of the largest species. The breadth of the 

 bone, from the base of the root to the outer surface, is an inch and a quarter, the 

 inner portion being estimated at the same, and the thickness of the tooth being 

 about an inch and an eighth ; where the tooth is present, the jaw is nearly three and 

 a half inches through. The great obliquity in the insertion of the teeth distin- 

 guishes it from other species, and the base of the crown of the tooth (Fig. 1} is 

 more circular. As I consider it differing from other American and European 

 species, I propose to call it Mosasaurus Caroliniensis. 



Since this paper was prepared, Professor Agassiz has kindly allowed me the 

 privilege of examining a portion of a jaw of a specimen from New Jersey, which 

 is figured of the natural size, in PL I. Fig. 2. It contains portions of two teeth, 

 with two of the successional teeth making their appearance above the alveolar 

 surface. The former as well as the latter are compressed laterally, a section of 

 the base of the crown being elliptical, not angular as in M. Couperi, 



The secondary teeth are much more compressed laterally, and the cutting edges 

 are minutely but regularly serrated, which, therefore, is a character of young teeth. 

 The investigations of Professor Agassiz induce him to consider all the specimens 

 from New Jersey as belonging to the same species, including that described by 

 Dr. Dekay, and named by Bronn Mosasaurus Dekayi, and which Dr. Morton had 

 provisionally called M. occidentalis. 



Of this species the specimen in the Academy of Natural Sciences, Philadelphia, 

 from Burlington, New Jersey, is a fine one, containing two nearly perfect teeth. 



Accordmg to our present knowledge of the genus Mosasaurus, we have in the 

 United States five species : — 



MOSASAURUS, Conyb. 



Mosasaurus Dekayi, Bronn, Lethaa Geogn., II. p. 760. Dekay in Ann. Lye. 



Nat. Hist. Neiv York, III. p. 135. (1830.) 

 Mosasaurus Maximilian:, Goldfuss in Act. Nov. Acad. Leap.- Ccesar. Nat. Curios., 



XIII. (1844.) 

 Mosasaurus minor, Gihhes: vide supra. 

 Mosasaurus Couperi, Gihhes : vide supra. 

 Mosasaurus Caroliniensis, Gihhes : vide supra. 



* Figure 3 has been inverted by the draughtsman. 



