24 FreLp Co_tumBpiaAN MuseuM—GEo .ocy, VoL. II. 
the bone comes in contact with the proximal end of the vomer; for a 
littie distance in front of this emargination, and distad to the pointed 
extremity of the bone, the border is slightly thickened for union with 
the vomer. Posteriorly, the rounded extremity of the bone is slightly 
thickened, and with sutural roughening for union with the ectoptery- 
goid process of the pterygoid. The outer border is slightly concave 
throughout nearly its whole extent; it is also thin for nearly its whole 
extent. Anterior to the small narial emargination, the bone forms a 
long, slender point. On the proximal end, the thin border is under- 
lapped by the thin anterior prolongation of the ectopterygoid for a 
distance of about fifty millimeters; the remainder of the extent comes 
in contact with the maxilla, but presents no distinct sutural surface, 
unless it be near the anterior extremity. There is no posterior pala- 
tine foramen. . 
The ectoptervgoid or transverse bone is of a slender, triangular 
shape. Its slender anterior end extends forward on the outer margin 
of the palatine. The posterior inner angle has a well marked sutural 
surface underlapping the pterygoid process. The outer extremity is 
thickened, curving somewhat downward to unite with the jugal, and, 
by a thin border, with the maxilla. 
The vomer is a very long, narrow bone, uniting with the palatine 
process of the pterygoids posteriorly by a squamous suture, and, for 
a short distance on the outer side posteriorly, with the slender 
pointed extremity of the palatine, the small narial opening intervening. 
They lie closely side by side, apparently without sutural union. 
They are concave above, and convex below from side to side, and are 
rather stout. The anterior ends are so concealed that they can not 
be described or frgured. - 
BraAin-cASE.— The lateral walls of the brain-case in the reptilian 
skull are composed of six distinct elements, according to the views of 
some comparative anatomists. Two of these may be fused with con- 
tiguous elements in the adult skull, or one or more of them may be 
entirely absent. Those elements supposed to contain the otic capsule 
were called by Huxley, in his lectures on the structure of the verte- 
brate skull (Elements of Comparative Anatomy, 1864), the epiotic, 
proétic and opisthotic. The other three are the supraoccipital, 
exoccipital and alisphenoid. The epiotic, Huxley homologized with 
the so-called epiotic of fishes and_batrachians, and, although indis- 
tinguishably united with the supraoccipital in all adult reptilian 
skulls*, he believed to be a distinct ossificatory element. ' This has 
* Parker describes the epiotic as a distinct element in 7yopfidonotus natrix. Phil. Trans., 
1575, Pp. 405. 
