lO 
BULLETIN OF THE LABORATORIES 
this process, which descends below the level of the jugal, a nearly ver- 
tical plate extends upward to form a sliding sheath which clasps the 
pres-phenoid and plays back and forward upon it. The flattened ends 
of the long (.50) pterygoids are fused with these vertical plates by ex- 
panded, overlapping plates. There are two curved flanges springing 
from the point where the pterygoids unite with the palatals. The eth- 
7 no-turhmal plates are more or less ossifled and are seen on either side 
of the rudiment of the vomer. The pterygoids are stout but very 
unusually long and, on account of the size and position of the quad- 
rate bones, are quite distant from the basis cranii. Near the point of 
union of the pterygoid with the quadrate bone, a small hooked process, 
about .12 long, extends upward from the former bone. What the use 
or the homologies of these processes may be, we do not know, although 
they occur in finches and in other birds. 
At the posterior of the two mandiblar processes of the quadrate 
bone is a bone as large as the head of a large pin, but of irregular 
shape, which may be regarded as either a sesamoid contributing to lock 
the jaw or an independent portion of the quadrate. There is also a 
very minute sesamoid at the union of the quadrato-jugal and the quad- 
rate. The lower jaw shows no evidence of its composite character. 
The whole anterior half is enlarged and forms a simple trough of can- 
cellous bone which may be assumed to consist of the dentary elements 
of both rami. The surangular, angular and splenial elements of the 
rami are not distinguishable. The articular portion consists of a huge 
flange, extending inward and upward and is perforated at the middle of 
its inner surface for the entrance of Meckel’s cartilage. 
What corresponds to the surangular portion is a broad triangular 
plate extending upward inside the jugal bones and serving to further 
lock the jaw. Thus, as we have seen, the whole skull is modified in 
harmony with the enormous rhinencephalic development. 
The hyoid arch is well developed and consists of seven bones, 
whose homologies, in the present state of our knowledge, cannot be 
made out. The anterior pair are pointed before and behind, and at- 
tached at the middle to each other and the end of the azygos bone 
which next follows. The first mentioned bones are called entoglossal^ 
by Gegenbaur, by some American authors, ceratohyals, with no real 
evidence that they are homologous with the bones so called in other ani- 
mals, The following element may be called basihyal {^copula of 
G^gQnbaiier,) and is flattened to form a vertical plate and bears on 
