jq5 Shufeldt, Osteology of Harris's Cormorant. [^^ "^"^ 



which is hkewise large and deep in the same location on the 

 humerus of P. urile, and, to a greater or less degree, seems to be 

 present in the case of all Cormorants. In Harris's the shaft 

 presents the same amount of sigmoid curve as it does in other 

 species, and we also find the peculiar, in-turned extension of the 

 ulnar trochlea of the distal extremity of the bone. 



In length, this humerus differs considerably in different 

 individuals, it being loi mm. according to Gadow, while in No. 

 19,628 of the specimens here being examined it is go mm. In 

 No. 19,719 it is 102 mm., being the same in No. 19,720, and so on. 



As Gadow has already pointed out in his memoir, the greatest 

 amount of reduction in the skeleton of the wing of this bird is to 

 be seen in the bones of the antibrachium, for, while the ulna and 

 radius are about of equal length, they are each very much shorter 

 than the humerus. Moreover, it is to be noted here that the 

 radius has lost the most of that peculiar double curve its continuity 

 presents in other Cormorants, and so well exemphfied in the radius 

 of P. urile. Here, as in other Cormorants, when normally articu- 

 lated, its distal moiety, or rather less, is parallel and close to the 

 ulna,' while the proximal half of the bone, from head to mid-shaft, 

 curves away from its companion in the forearm, and thus creates, 

 in that locality, a large " interosseous space." 



With a gently curved shaft, which has double the calibre of 

 that of the radius, the ulna of Nannopterum has lost much of that 

 conspicuous process seen in other Cormorants, which curves about 

 the head of radius and supports the facet of the lesser sigmoid 

 cavity. Proximal fourth of this shaft, on its palmar aspect, is 

 scooped out longitudinally to an extent both actually and 

 relatively greater than we see it in other Cormorants, while the 

 insertional points for the quill-butts of the secondary feathers 

 are shallow pitlets rather than papillae, as they are in P. carbo 

 and its congeners. In P. urile these papillae are paired, thus 

 creating a double row down the shaft in this and probably in 

 other species of these birds. 



Radiale and ulnare of the carpal joint are rather large in pro- 

 portion, as compared with the bones with which they articulate ; 

 but this is so shght that it would hardly be safe to say that their 

 reduction had not proceeded quite so far, relatively, as the other 

 bones with which they are in contact, although, judging by the 

 eye alone, this appears to have been the case. If it be so, it is 

 very slight. However, the transverse diameter of the ulnare 

 enters into the length of the ulna's shaft in P. carbo eighteen 

 times, while the corresponding diameter of the ulnare in Nannop- 

 terum enters into the length of the shaft of its ulna less than ten 

 times. 



Apparently there does not seem to have been the same amount 

 of shrinkage, in proportion, in the case of the bones of manus 

 as there has been with respect to the humerus and the radius 

 and ulna of the forearm. The clawless terminal joints of the 

 thumb and two fingers are all present, having been retained in 



