BHUFELDT.] OSTEOLOGY OF THE TETRAONIDA. 679 
just anterior to the bases of the diapophyses, are the four subelliptical 
and concave facets of the capitula of the dorsal pleurapophyses. From 
their upper and posterior points sharp crests run beneath the transverse 
processes to meet the out-turned and cordate facets at their extremities 
for the tubercula of the ribs. At regular intervals, and nearly in a 
right line among the diapophyses, are the elliptical orifices for the 
transmission of the dorsal nerves. 
Pneumatic foramina are found about the bases of the transverse pro- 
cesses, the most anterior one being of some size. 
The centra of these amalgamated vertebre are very much compressed 
from side to side. This compression has its due influence upon the form 
of the neural tube within, while the bone below is produced downwards 
into an excessively thin and sharp crest, which is still further extended 
into four inverted T-shaped hypapophyses of large size. They join each 
other beneath to a greater or less degree in many of the genera. This 
union more frequently takes place between the first and second, and the 
first is always upturned and flanged out laterally, a feature prominently 
reproduced in Lagopus and Bonasa. These winglike side extensions of 
the lower margins of the hypapophyses not infrequently are continued 
on two or three consecutive ones, and are sometimes the widest on the 
second.—Canace. 
Both in the Grouse and Partridges we find a free vertebra inserted 
between the compound bone we have just been discussing and the first 
sacfal vertebra. This segment we must consider as belonging to the 
dorsal series, although in Cupidonia and Pediecetes the upper and distal 
aspects of its diapophyses are more or less moulded to conform with the 
ilia. This bone is also figured in Plate VI, Fig. 55, in conjunction with 
the other dorsals, with which it has all its characteristics in common, 
and such ones superadded as we might expect to find in a vertebra 
naturally disjointed in the middle of the column. It has the longest 
diapophyses of any of the series to which it belongs; facets for the 
tubercula and capitula of its own free pleurapophyses; a hypapophysis 
of no mean length that may or may not be expanded below. 
Metapophysial spiculz on its transverse processes sometimes are so 
far produced as to reach vertebrae before and behind it. 
This segment is likewise pneumatic. 
There is a wonderful vein of regularity running through the dorsal 
pleurapophyses, hemapophyses, and hemal spine orsternum. As to 
the first pleurapophysis, or rather the first pair of these bones, we have 
already described them as they are found in the ultimate cervical. 
There we are aware it never reaches the sternum by the intervention of 
a sternal rib; that they are usually found to possess thoroughly devel- 
oped heads and tubercles for the vertebra, their shafts being less Hat- 
tened than the dorsal ribs, and only in Lagopus did we discover any 
epipleural appendages. 
As far as our observations extend, the consolidated portion of the 
column of the dorsum has always consisted of four vertebre, and con- 
sequently we find in this portion four pairs of movable dorsal pleura- 
pophyses and one pair for the free dorsal vertebra, reckoning five alto- 
gether for this region. The first pair of dorsal vertebral ribs terminate 
in free extremities, which are usually in line with the inter-hzma-pleura- 
pophysial articulations in old specimens, and as a rule support epi- 
pleural appendages, characteristic of the species to which the rib 
belongs. 
In the Tetraonide, following the general aphorism of the class, we ob- 
serve a gradual dilatation of the skeleton from the inter-coracoidal aper- 
