MOSASAURUS. 33 
most important remains, comprising the greater part of a skeleton, consisting of a 
nearly entire skull and eighty-seven vertebrae, were found, by Major O'Fallon, on 
the Upper Missouri, in the vicinity of Big Bend, and were presented by him to 
Maximilian, Prince of Wied, who was then travelling in America. Conveyed to 
Europe, the remains were presented by the Prince to the Museum of the Academy 
of Naturalists of Bonn, and were described in the Transactions of the Academy by 
Dr. August Goldfuss.' 
Cuvier views the skull of the great Maestricht Mosasaurus as intermediate in 
anatomical characters to that of the existing Monitor and Iguana.? The length of 
the lower jaw he gives as three feet nine inches,* and estimates the skull to have 
been nearly four feet. On each side of the lower jaw there are fourteen teeth ;° 
to the upper maxillary bone eleven teeth, and as it is estimated that there may have 
been three additional teeth to each side of the inter-maxillary bone, the number 
would be the same in the upper as in the lower jaw.° ‘The pterygoids, as in the 
Iguana, also possess teeth, of which Cuvier states there were eight to each bone.” 
The skull of the Missouri Mosasaurus is about half the length of that of the 
Maestricht Mosasaurus, but Dr, Goldfuss assumes too much when he says the com- 
plete ossification of all parts, as well as the frequently perceptible solidification of 
the teeth, prove that the individual had reached maturity, for the skull and teeth 
of Saurians exhibit the same characters of ossification and development from youth 
to extreme age. As remarked by Owen, “the characters of immaturity are not 
manifested by the cold-blooded animals in their osseous and dental systems as they 
are in the warm-blooded and higher organized mammalia.’” 
In the jaws of the Missouri Mosasaurus there are the remains of eleven teeth 
above and below, and supposing three more to have existed in the anterior extremi- 
ties of the jaws, which were lost, the number would be equal to that of the Mae- 
stricht Mosasaurus. The pterygoid bones, according to Dr. Goldfuss, are each 
occupied with the remains of ten teeth, being two more than the number mentioned 
by Cuvier as existing in the Maestricht skull. 
The vertebrae of Mosasaurus have their bodies concave in front and convex behind. 
Cuvier" estimates the number to have been about one hundred and thirty-three. 
These he divides as follows: The atlas and axis; eleven vertebrie of the neck and 
thorax distinguished by the presence of an inferior apophysis or hypapophysis 
together with articular and transverse processes; five similar vertebre without the 
vertebra, represented in Fig. 34a, referred to Macrosaurus, the tooth, represented in Fig. 39, referred 
to Polyptychodon rugosus, and that represented in Figs. 45, 46, which I referred to a reptile of un- 
known relation with the name of Drepanodon impar, I also suspect to belong to Mosasaurus. 
* Schidelbau des Mosasaurus. Nov. Act. Acad. C. L. C. Nat. Cur., Vol. XXI, p: 73. 
2 Ossem. Foss., Ed. 4, T. 10, p. 150. 8 Tbid., p. 168. “Thid} ps 151: 
5 Ibid., p. 139. 6 Tbid., p. 143. 7 Ibid., p. 148. 
* “Die vollstindige Verknécherung aller Theile, so wie die hiufig bemerkbare Ausfiillung der 
Zihne beweisen, dass das Individuum seine vollstindige Ausbildung erreicht hatte.” Schidelbau 
des Mosasaurus, Nov. Act. Acad. C. L. C. Nat. Cur., Vol. XXI, p. 177. 
® British Fossil Reptiles, p. 187. 20 Ossem. Foss., T. 10, p. 165. 
5 April, 1865, 
