Osteology of Circus hudsontus. oy 
bone and the distal ends of ulna and radius are found the usual 
carpal ossicles the w/nare and radiale. ‘They differ in no marked 
respect from the bones as found in nearly related forms, or in some 
of the Owls. 
The follex has but one phalanx awarded it, but this bone is 
broad and strong, presenting a considerable articular surface for the 
metacarpus. This phalanx may support a claw at its extremity. 
Second digit has two phalanges, the usual one with posterior border, 
and the lower, long pointed one. In the former the expansion alluded 
to is surrounded by a prominent raised margin, but the area it en- 
closes is not perforated as in some birds. ‘The little bone of ¢hird 
digit has a process developed upon its posterior edge, which I 
have noticed in other birds, and will have something to say about 
on a future occasion. 
Of the PelvicLimb: As in the upper extremity so we find it 
to be case here in this member,—it is only the /emur of the seve- 
ral bones of the limb, that is pneumatic. A neat, elliptical 
orifice is found on the anterior surface of the bone about the mid- 
dle of its upper third between the trochanterian ridge and the 
anterior muscular line. ‘This is its usual site when present in 
birds, and here admits air throughout all parts of a comparatively 
large, but very light bone. 
The head of this femur is rather small, and placed at a slight 
angle on the shaft. Above, it is well excavated for the hgamen- 
tum teres, between which concavity and the trochanterian ridge, 
here but slightly elevated, we find the broad articular surface for 
the antitrochanter of the pelvis. Its breadth increases as it 
recedes from the head of the bone, and is carried slightly over the 
summit of the ridge. 
This bone is gently arched throughout its length, the concavity 
being upon its posterior aspect. Its shaft is very smooth, for the 
most part cylindrical on section, and but faintly shows the usual 
muscular lines adown its length; the most distinct one passing 
from the fore part of the trochanterian ridge to the outside boun- 
dary of the inner condyle. At the anterior aspect of the lower 
third of the shaft, we observe that the ridges which are the 
beginnings of the condyles are parallel with each other until they 
disappear at the lower end of the bone. They are quite promi- 
nent and thus give rise to a well marked ‘‘rotular channel.’’ A 
very noticeable thing about the femur of Czvcus is that the con- 
