206 NEW YORK STATE MUSEUM 



side. The pneumatic fossa is very capacious, while its internal 

 walls are studded with small pneumatic foramina. The humeral 

 head is large and tuberous, and is separated from the ulnar crest by 

 a transverse and deep valley. A rather short and small radial crest 

 is bent abruptly palmad. At the distal end of the bone prominent 

 " oblique " and " ulnar tubercles " are to be seen. The olecranon 

 fossa is rather shallow in the humerus of Centrocercus, not being 

 as well marked as it is among the Perdicinae. Few or no distinctive 

 points are to be found upon this bone among the Tetraoninae, except 

 in the matter of size ; Tympanuchus, which has rather a heavy 

 skeleton, has a humerus which is moderately robust in accordance. 



The radius of a large cock Centrocercus has a length of 10 centi- 

 meters, the bone presenting us with no peculiar characters. Ulna is 

 still longer, measuring a fraction over n centimeters. It is a stout 

 bone with massive extremities, and presents a row of papillae 

 down its shaft. In the adult we find the two usual ossicles, the 

 radiale and the ulnare composing the wrist joint, and a faithful 

 representation of the carpometacarpus as' well as all the other 

 bones .mentioned is given in my Hayden papers. Short pollex 

 digit may occasionally support a diminutive claw, but it does not 

 always come through the integuments which cover the phalanx. 

 The process on the back of the shaft of the index metacarpal I here 

 propose to call the indicial process, and will have something to say 

 about it further along. Posteriorly, the proximal joint of index 

 digit is considerably expanded, and is imperforate. A stout tri- 

 hedral joint completes the fing-er in question; while a stumpy, com- 

 pressed phalanx belongs to the medius digit. 



W. K. Parker published an admirable memoir in 1888 in the 

 Philosophical Transactions of the Royal Society of London, en- 

 titled " On the Structure and Development of the Wing in the Com- 

 mon Fowl." In the present connection I .will quote somewhat ex- 

 tensively from that paper, and alter the letters of reference so as to 

 make them as far as possible referable to my figures 57, 58 and 59 

 [p. 706], plate 7, of my memoir on the " Osteology of the North 

 American Tetraonidae " which appeared in the Tzvelfth Annual Re- 

 port of the United States Geological and Geographical Survey of 

 the Territories (F. V. Hayden), part 1, Washington, 1883. Parkei 

 says : 



I find that the two persistent carpals of the bird's wing, the radiale 

 and ulnare of authors, show evidence of being compound structures, 

 probably containing within themselves remnants of an intermedium 

 and a centrale. 



