802 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. 



of their character has been due to Professor Marsh, and that of the ante- 

 rior limbs to myself. Professor Owen writes as follows (p. 710) : — "The 

 determinations by Cuvier of certain bones and portions of bone iu the 

 original Camperian collection of remains of the Maestricht Mosasaur, 

 as scapula, coracoid, pubis, antebrachial, carpal, and phalangeal bones, 

 established the capital fact that it was a reptile with both scapular and 

 pelvic arches and their appended limbs. Evidence had been obtained 

 at the date of the Bridgewater treatises to enable Buckland to define 

 these limbs as flippers like those of the Plesiosaur. The subsequent 

 discoveries of Professors Cope and Marsh have confirmed these deter- 

 minations", etc. "But the number of the digits in each limb, and of 

 the phalanges in each digit, remain to be determined." Since Professor 

 Marsh and myself have shown that every one of the determinations of 

 limb-bones by Cuvier was erroneous, it is difficult to see that the credit 

 of their discovery belongs to him. Thus, his "pubis" is an ischium; 

 his "scapula" (fig. 9) is a coracoid; his "scapula and clavicle" is a 

 coracoid probably of a species of Platecarpus ; his "ulna" is an ilium ; 

 his "carpals" are ulna and phalange respectively; while his supposed 

 phalanges, if truly such, do not belong to Pythonomorphous reptiles. 

 If we add to this that he represents what he calls an "ungueal pha- 

 lange", a structure which does not exist in the order, we are forced to 

 the opinion that if Cuvier did discover the scapular and pelvic arches 

 of these reptiles, he was not truly aware of it at the time. The state- 

 ments of Buckland, and similar ones by Pictet, as to these limbs, are 

 not accompanied by any references or demonstration to show that they 

 are anything more than guesses on the subject. Nor does Professor 

 Owen make any better exhibit in this field. In an ingeniously worded 

 sentence (p. 683), he states that he referred fossils from Kew Jersey, 

 which included " phalanges of a limb of a natatory character", to the 

 genus Mosasaurus, and the inference is necessary that at that time he 

 determined the limbs of that genus to be of natatory character. On 

 reference to the essay cited,* I find the fact to be quite the reverse. I 

 quote the language of Professor Leidy t in regard to it, as follows : — 



" Professor Owen,| after remarking that no part of the organization 

 of Mosasaunis is so little known as that of the locomotive extremities, 

 and substantially quoting the views of Cuvier expressed above, enters 

 into the description of some long bones of the extremities, 'showing 

 the Lacertian type of structure', which were obtained in the green-sand 

 formation of New Jersey. Professor Owen observes, 'On the highly 

 probable supposition that these bones belong to Alosasaurus, they in- 

 dicate the extremities of that gigantic lizard to have been organized 

 according to the type of the existing Lacertilia and not of the Unalio- 

 sauria or GetaceaP^ 



In reference to Professor Owen's assertion that the number of pha- 



*Quar. Journ. Geol. Soc. v. 1849, p. 3^0. 



t Cretaceous Reptiles of North America, p. 42. 



\ British Fossil Eeptiles, p. 190. 



