SHUFELDT : OSTEOLOGY OF THE STEGANOI'ODES 173 



is more expanded, and it has a broadly developed " costal process." In the case with 

 the scapula, we find that the blade of it in the Cormorant is not as much curved, 

 nor is the distal end of the bone at all bent outwards. (See Fig. 16.) 



On the Appendicular Skeleton of P. urile. 



Very little of the skeleton of this Cormorant is pneumatic. For the most part 

 the bones are solid and heavy. Apparently air gains access only to certain parts of 

 the cranium and lower jaw, other bones of the osseous system being completely non- 

 pneumatic. This is especially true of the skeleton of the limbs, where all the bones 

 typify in the highest degree the un aerated variety. 



In a number of respects the bones of the pectoral limb of P. urile present char- 

 acters which essentially agree with those upon the corresponding bones as found in 

 the arm of an Anhinga, which characters have already been described above. In 

 the humerus of Phalacrocorax, however, which is shorter than the ulna, the " pneu- 

 matic fossa" is profoundly concave, quite as much so as in those large species of 

 birds in which the bone is pneumatic, or even more so than in some which show that 

 condition. At its distal end the articular protuberance for the radius has an elon- 

 gation at its proximal extremity which is bent over towards the mid-longitudinal 

 axis of the shaft of the bone. The "oblique tubercle" for the ulna is more hemi- 

 spherical than we usually find it in birds. At the proximal end of the ulna we ob- 

 serve a conspicuous projecting lip of bone, which contributes an additional surface 

 for the radial articulation. Papillae down the shaft of this bone for the quill-butts 

 of the secondary feathers are in a single row and rather feebly developed. Both 

 radius and ulna are somewhat bowed, and when articulated in situ they are in con- 

 tact for their distal moieties while proximally a good-sized spindle-shaped interosse- 

 ous space occurs between them. 



The characters of the skeleton of the hand are practically the same as we found 

 them to exist in the manus of Anhinga. There are no distinguishing characters of 

 any importance. 



Gannets have the skeleton of their pectoral limbs in many respects like the 

 Cormorants and Darters, but in them all the bones are completely pneumatic. 

 When we come to consider the difference in the habits of the representatives of the 

 three families, this is not so much to be wondered at. 



Cormorants are more or less like the Darters too, in the osteology of their pelvic limb. 

 There are more differences, however, to be found here than we discovered upon compar- 

 ison of the pectoral extremities. Phalacrocorax has the femur proportionately stouter, 

 shorter, and more bowed in the antero-posterior direction than it is in Anhinga. 



