Osteology of Circus hudsonius. 7 
ences are smooth and somewhat prominent. Venous grooves are 
seen running over them and leading to minute foramina just within 
the orbital margins. 
The superciliary processes of the lacrymals are well seen upon 
this view, and it is to be noticed that their outer extremities sup- 
port ‘‘ accessory pieces,’’ as in some other falconine forms ; more- 
over, these bones are very loosely articulated with the frontals on 
either side, and they are sure to come away in the course of ordin- 
ary maceration. From above we can also see the aliethmoids and 
the palatines extending back of them, as well as the anterior mar- 
gins of the quadrates with the zygomatic bars leading from them. 
The maxillaries show also upon this view, just beyond the lacry- 
mals. 
One of the most striking features upon basal view of the skull of 
Circus is, how all the bones he nearly in the same horizontal plane, 
this plane extending from the posterior margin of the foramen 
magnum to the descending hook-like process of the beak formed 
by the premaxillary. This feature is quite characteristic of some 
of the other genera, but not to the extent as seen in this Harrier. 
Just within the point of the beak are four small foramina, ar- 
ranged as if they occupied the angles of a square. These open- 
ings are seen in other Hawks and Falcons. Immediately behind 
them we see in C7vcus the space where the palatines and maxillo- 
palatines merge into the premaxillary. On either side, and 
external to this, is a foramen formed by the bones surrounding it 
—the maxillary, the palatine and the dentary process of the pre- 
maxillary. 
The major part of the fa/atines lie in the horizontal plane ; 
they are broad behind, where they are marked on their inferior 
surfaces with shallow depressions, to run out into narrow bars 
anteriorly. ‘The interpalatal space is broad, being fully three mill1- 
inetres across its narrowest part. In this space we see the vomer 
and the maxillo-palatines. A small part of the palatines poste- 
riorly curve upwards, affording by their firmly united superior 
surface a concave groove to ride upon the rounded surface offered 
by the anterior half of the rostrum, while beyond this they 
anchylose in the median line with the vomer (Fig. 3). The 
articular heads of the palatines also rest upon the rostrum, side 
by side, with their facets looking almost directly backwards to 
articulate with the pterygoids. 
