106 



BULLETIN 110, UNITED STATES NATIONAL MUSEUM. 



extending farther forward than the inner which is broadest transversely. The 

 dorsoventral expansion of this end is only one-half that of the proximal end. 



The proximal phalanx of digit III closely resembles the one described above, 

 except that the dorsoventral expansion of the proximal end is much less, measuring 

 only 20 mm. The distal end is also narrower transversely, though it has the same 

 unequal development of the articular facets. These would appear to indicate a 

 turning in toward the body of the extremities of the three first digits of the hand, 

 instead of extending straightforward, as shown in figure 62. 



The proximal plialanx of digit IV has a slightly expanded proximal end that 

 articulates with a cupped end with metacarpal IV. The distal end is nonexpanded, 

 presentmg a trmicated end that may support a terminal phalan.x, but probably noth- 

 mg more than a pointed bony ossicle. I doubt the presence of three phalanges on 

 this digit as restored by Marsh (fig. 58). 



Measurements of the left fore foot elements of Ceratosaurus nasicornis Marsh. No. 4735, U.S.N. M. 



METACARPALS. 



PHALANGES — FIRST ROW. 



Greatest length 



Greatest width, jjroximal end. 

 Greatest width, distal end. . . . 



28 

 21 

 20 



27 

 22 

 16 



17 

 12 



7 



Plates 21 and 23. 



The pelvis of Ceratosaurus nasicornis Marsh, is one of the most perfectly pre- 

 served among the Theropoda. The ilia, ischia, and pubes are firmly coossified, so 

 that their relative positions have never been called into question. The ilia were 

 securely attached to the sacrum, which was found in its natural place in the skeleton. 

 The extremely small size of the pelvic orifice is one of the marked features of the 

 carnivorous group as contrasted w^ith the large opening in the herbivorous dino- 

 saurs found with them. If the Tlieropoda were viviparous, as some facts seem to 

 indicate, one difficidty naturally suggested in the case of a reptile is removed. 



The coossification of these pelvic bones does not appear important as a diag- 

 nostic character; far more probable that it represents an individual characteristic 

 due to advanced age, such as is occasionally found in tlie Sauropoda; as, for example, 

 a specimen of Diplodocus in the Carnegie Museum, Pittsburgh, has the pubes 

 coossified with the pubic peduncle of the ilium. 



