Fossil Birds in the Marsh Collection of Yale University 61 



of a right humerus (Fig. 94), and the proximal end of a left femur 

 (same individual?) Fig. 96). Accompanying it there is found a fossil 

 imperfect fragment of bone of some other vertebrate which I have 

 not made out (Fig. 97). 



These fossil remains represent a pheasant closely related to 

 Phasianus colchius, with which I have critically compared it (No. 

 19293. Coll. U. S. National Museum, <^). 



With respect to the humerus, the characters are almost identical, 

 the opening of the pneumatic foramen in P. mioceanus being much 

 smaller than in the existing species. This feature, however, is quite 

 unimportant. A better marked difference is seen in the head of the 

 bone, it being somewhat thicker, broader and larger in P. colchius 

 than it is in the extinct species. In the latter, too, the shaft of the 

 bone is a trifle stouter. 



With respect to the proximal end of the femur (Fig. 96), I may say 

 that it is imperfect to the extent of being chipped and worn in several 

 places; otherwise it presents almost identically the same form as the 

 corresponding part of the femur of Phasianus colchius. What is 

 remarkable, however, in the fossil specimen is that there is not the 

 slightest evidence of the presence of a pneumatic fossa, as there is in 

 the existing species, where it is a very prominent feature, being a 

 large, elongate fossa between the head of the bone and the great 

 trochanter. Its base is perforated by some eight or ten pneumatic 

 foramina, and the entire bone is permeated by air. The head of the 

 fossil femur, or rather the entire end of the bone, was solid, and this, 

 the upper part of the shaft, presents no evidence of ever having been 

 hollow. Indeed, were it not for the fact that, in all other respects, 

 this fossil agreed so closely, morphologically, with the existing species, 

 I would have suspected this fossil proximal end of the femur to have 

 belonged to some other animal — perhaps a mammal — and this sus- 

 picion would have been strengthened by the presence of the uniden- 

 tified fragment of fossil bone shown in Figure 97, which has the appear- 

 ance of the vertebral end of a mammalian rib of some sort or other. 

 However, there is no cjuestion in the world about the humerus, as 

 may be readily beheved on comparing Figures 94 and 95 of Plate 

 XIII; and if this specimen was associated with the proximal end of a 

 femur which — apart from being completely non-pneumatic and the 

 pneumatic fossa entirely absent — agreed morphologically in all other 

 respects, it would, to say the least, constitute a most extraordinary 

 coincidence. 



Many birds in the present-day avifauna possess pneumatic humeri 



