OSTEOLOGY OF BIRDS 



231 



but very much like the skeleton as we find it in some of the larger 

 forms of the true fowls [see pi. 1, fig. 11 ; pi. 2, fig. 19; pi. 3, fig. 20 

 and pi. 8, fig. 32]. In its vertebral column it has in the cervical 

 portion 15 free vertebrae, the 15th bearing a pair of small free 

 ribs. The 16th cervical coossifies with the three following dorsal 

 vertebrae into one solid bone. This 16th vertebra I call a cervical 

 one for the reason that its ribs do not reach the sternum, although 

 it has large epipleural appendages. It has no costal ribs to effect the 

 connection [pi. 3, fig. 20]. The fourth dorsal vertebra is a free one, 

 but its ribs like the pair anterior to it, have no epipleural appendages, 

 and their costal ribs do not quite reach the sternum, but articulate, 

 on either side, with the costal rib preceding it. There appear to 

 be 16 vertebrae in the " pelvic sacrum," and there are four free 

 caudal vertebrae, and in addition thereto an immense long and 

 pointed pygostyle. 



Both the sternum and the pelvis in Argus very largely agree in 

 their morphology with those bones in Gallus, and the pelvis in par- 

 ticular, departing- somewhat from the style of that bone in Phasi- 

 anus, is more or less typically galline, and widely different from the 

 pelves of such forms as Centrocercus, Pediocaetes, and other genera 

 of the Tetraonidae. A prepubic process is more or less conspicu- 

 ously developed in all of these galline birds, and especially in the 

 Asiatic genera and others in the East. To this, Argus and Phasi- 

 anus form no exception. The skeleton of the limbs in A r g u s 

 giganteus is powerfully developed, but particularly the bones 

 of the pectoral limbs [pi. 8, fig. 32]. Both the peculiar plumage 

 and the habits of the fowl demand this, and the necessity for it 

 has been beautifully carried out. In the pelvic limb, both the tibio- 

 tarsus and the tarsometatarsus are long and comparatively slender. 

 A small patella is present, and a sesamoid nearly as large is found 

 at the back of the ankle joint, just above the hypotarsus of the 

 tarsometatarsus. 



The pneumatic femur has a length of about 10.3 centimeters ; the 

 tibiotarsus 16 centimeters; and the tarsometatarsus 10.5 centimeters. 



Passing to such a species as R o 1 1 u 1 u s r o 11 1 r o 11 1 I find that 

 it possesses a very delicately constructed skeleton throughout, and 

 while presenting all the typical characters of a true gallinaceous 

 form, it comes nearer, osteologically, to the North American Per- 

 dicinae than anything I have heretofore examined. Its entire 

 skeleton is very much indeed like some big Callipepla, or a Loph- 

 ortyx. In Rollulus the six caudal free vertebrae are greatly re- 



