18 



BULLETIN 73, UNITED STATES NATIONAL MUSEUM. 



STERNUM. 



The sternum presents no diU'erences of importance from that of M. Indent 

 figured by Grieg," except that the fourth and fifth segments are anchylosed together, 

 both laterally and transversely, and that the two sides are symmetrical. (PI. 13, 

 fig- 2.) 



PECTORAL LIMB. 



The scapula of M. europseus presents an entirely' different appearance from 

 that of 21. bidens as figured in Van Beneden and Gervais' Osteography (plate 22). 

 In europseus the scapula is very high anteriorly, the anterior border is convex forward 

 and the anterior crest convex backward, bounding an elongated elliptical area. 

 The posterior margin is straight. The acromion is short, with convex margins at 

 the base, beyond which it narrows suddenly and terminates in a straight, cylindrical 

 process, which is strongly inclined upward. The coracoid is as long as the acromion, 

 nearly straight and horizontal, but expanded at the end. (PI. 13, figs. 3, 4.) 



The phalangeal formula of the Atlantic City specimen of if. europseus and those 

 of three Norwegian specimens of J/, bidens are as follows (the metacarpals being 

 included): 



Phalangeal formula of M. europnus and bidens. 



In M. europseus the metacarpal of the third digit is much constricted in the 

 middle. The shaft of the ulna is straight. Except in these particulars and the 

 relatively small size of the whole pectoral limb, the latter appears not to differ 

 materially from that of M. bidens. As shown above, the first digit in M. bidens 

 consists of the metacarpal bone only, while in M. europseus a phalange is also present. 



Dimemions of the skeleton of the Atlantic City specimen of M. europxxis, No. 23346, U.S.N. M. 



mm. 



Length of the seven cervical vertebrae b 94 



Length of first, second, and third cervical vertebrae b 45 



Atlas: 



Greatest breadth ^50 



Greatest height jq3 



Height of neural canal 31; 



Greatest breadth across anterior articular facets 96 



Axis, greatest breadth J44 



" Bergens Mus. Aarb., 1904, No. 3, p. 32, fig. 12. 

 b Placed in contact. 



