No. 409.] THE SAND GROUSE. 13 
The form of the premaxillary is gallinaceous, the sutural 
traces of its proximal frontal process being distinct throughout 
life over the facial frontal region in the middle line, as we see 
it in many fowls. The large narial openings are elliptical in out- 
line, and made even more so by a curled osseous extension 
upon either side of the inner nares, that is, above and in front 
of the very large pars plana, below and in front of the frontal, 
touching the nasal externally and the premaxillary internally, 
while its upper part, with its free anterior edge, is in full view 
upon superior aspect of the skull. A few small, irregular 
vacuities may occur in the interorbital septum, but the good- 
sized orbit has upon all sides well-defined bony walls, the 
frontal roof overhead being well produced, the pars plana large 
and concaved upon its posterior aspect, the anterior part of the 
brain-case complete; while quadrate, pterygoid, and palatine 
afford a fairly good osseous floor. 
The postfrontal processes are more or less aborted, and the 
squamosal ones are thin and lamelliform, as in the chickens, — 
the two apophyses not coming in contact distally. 
At the base of the skull the palatines are of extremely 
slender construction, and widely separated from each other in 
the middle line. They do not even come in contact across the 
sphenoidal rostrum, which latter is much thickened and rounded, 
being pointed anteriorly, where it is carried beyond the pars 
plana. 
Either maxillo-palatine is a mere rudimentary spine, so small 
that the thread-like anterior rod of the corresponding palatine 
almost conceals it from view, when the skull is looked at from 
this side. A pterygoid is also very slender, and presents a 
somewhat flattened sigmoid curve at its middle part. These 
bones articulate with pteryapophysial processes at the cranium’s 
base. No vomer seems to be present, and the nasal septum 
is but very imperfectly performed in bone. 
The zygomatic arches are slender and straight, while the 
quadrates are well developed and present no very unusual 
characters. 
The mandible, of a V-pattern, resembles to no small extent 
that bone in some of the smaller ptarmigans (Lagopus). A 
