Osteology of Circus hudsonius. II 
rior extremities with cartilage. No doubt but that the uro-hyal 
is also tipped with this material, and it has been lost in my 
specimens, as I see such is the case in the Falcons, (falco r. 
gyvrfalco). 
Circus presents the desmognathous type of structure so far as its 
palate is concerned, and falls within the group Aélomorphe of 
Huxley. 
Not having a nestling of this Hawk at hand I am unable to say 
definitely whether the ‘‘ median septo-maxillary’’ ossifies as a dis- 
tinct element or not,—that it is present in the adult there is no 
doubt. The desmognathism in C7rcws, and the union of its maxillo- 
palatines with the nasal septum takes place beyond the broad pro- 
cesses thrown off by the maxillaries, while the spongy part of the 
maxillo-palatines are produced far backwards with a narrow valley 
between them. 
This arrangement is very different in /a/co, where the fusion of 
the maxillo-palatines is entirely opposite the maxillary processes, 
if anything somewhat more posterior to them, and, after their sep- 
aration, the intervening valley is much wider. 
I have failed to detect in Czzvcws either a medio-palatine or the 
mieso-pterygoids, that is, as I interpret these elements as they have 
been described by others. ‘To still further pursue our recapitula- 
tion of the characters presented in the skull of Czrcus, it is to be 
inferred from the presence of the rudimentary basi-pterygoidal pro- 
cesses of the sphenoid, that this Harrier, (the condition being an 
approach towards the more embryonic types,) stands among the 
lowest of the birds of prey. There is no evidence of the presence 
of these processes in the skull of /alco ry. gyrfalco. I would say 
then (were we to judge from this character alone), that this Falcon 
stood higher in the scale of organization than C7rcws does. ‘I'he 
style of the vomer has been sufficiently dwelt upon. The inner 
condyle of the quadrate is lower than the outer, and at the same 
time the smaller of the two. 
Parker tells us that ‘‘in the Sparrow-Hawk distinct pterotic and 
sphenotic centres are developed ; and the orbito-sphenoids are pre- 
ceded by cartilage.’’ (‘‘ Morph. of the Skull,”’ p. 264). 
On the Axial Skeleton (Figs. 7-10).—The cup for the occipital 
condyle on the anterior aspect of the a//as of Czrcus presents a dis- 
tinct notch in its superior periphery. Above it, the neural canal 
is a transverse ellipse, the neural arch closing it superiorly being 
