THE FOSSIL AVIFAUNA OF THE 
41 ." 
than at present exist in P. p. colwnbiamis, which would seem to jwjint to 
P. lucasi and nanus being the more nearly alfined forms. It is especially unfor- 
tunate that no skulls, sterna, or pelvis belonging to these species were discovered ; 
they would have shed no little light upon the subject of their true kinship. The 
measurements are in millimetres. 
P. Im^asi. 
P. naniw. 
Length of tarso-metatarsus 
44 
:« 
Greatest transverse diameter of proximal end 
11 
t» 
Greatest transveree diameter of trochlear extremity 
11 
10 
Pedioccetes nanus has proven to be the smallest species of the Gallinec coIlect«*d 
thus far in the Silver Lake I'egion, and I found no fossil remains of either tlie 
Ptarmigans or the Perdicincs. During my examination 1 made fretpient compari- 
sons with skeletons of the existing genera Dcndragapus and Pomisa, two or tliive 
species of each being in my jjrivate collection. (P'igs. oG and ?>7, PI. XVII.) 
Pliocene of Oregon : Cope collection. 
PA.LV.OTETRIX GILLI gen. et. sp. uov. 
In that part of the collection which was made by Mr. 8terid)erg at Fos.‘<il 
Lake, I found the right carpo-metacarpus of a Grouse that was new to me. 'I'lie 
specimen belonged to an adult individual, and in fo.ssili/.ing has turned nearly pure 
white. In* some instances the specimens that lielong to the older forms of l>iial.s 
of this horizon exhibit that character, but it is by no means always the ca.se. 'I'lie 
specimen now being considered is nearly perfect, and evidently Ixdonged to .some 
tetraonine form that in point of size was smaller than an adult female Ccnlro- 
cercus ttrophasianus, and conspicuously larger than the largest of our other exist- 
ing species of Grouse ; Tympanuchus for example. 'Phis being the ca.se it is 
unnecessary to compare it with any of the smaller Grouse or the Ptarmigans. 
Apart from the question of size then, it differs from Ccntrocercus in one very 
marked character, for we find that the articular surface at the summit of the Ihiuc 
on the outer side is continuous with that other articular surface found uimui the 
outer aspect of the proximal end of the medius metacarpal. In Pu/ecoMrix this is 
distinctly interrupted, and the first mentioned portion of the articular surface 
terminates posteriorly in a raised, rounded border. This latter character is most 
nearly approached by Pedioccetes, and to a lesser degree by Tywpanuchus, hut is 
exactly alike in none of them. It is very probable indeed that such a well marked 
character as this was associated in the skeleton Palccotctrix with excellent di.s- 
tinctive generic characters even stronger than it. More remains of the species, 
however, must be discovei-ed before this question can k* decided, and thesi' no 
doubt will come to light in due time. I find the length of the carisMiietacarpus in 
Ccntrocercus, Palccotetrix, and Tympanuchus to be 50, 40, and 40 millimetres, 
respectively, the first named being chosen from an adult female. (.See Fig. :55. IM. 
