The Cranial Nerves of Varanus bivittatus. 457 
posterior border of muse. rectus lateralis, where they enter the 
muscle about mid-way of its length. 
V. Nervus trigeminus arises as a double stem from the mid- 
lateral line of the medulla oblongata in its anterior region, It 
emerges from the brain cavity immediately, through a special open- 
ing, the foramen prooticum (GAupp), between the prootie bone and 
the membranous portion of the wall of the brain cavity, at a point 
just posterior to the union of the dorsal end of the columella with 
the prootic bone. Before it has fully emerged from its opening the 
nerve enlarges into a double ganglion, the »ganglion Gasserii«, of 
which the dorsal and lateral portion is larger than the median and 
ventral portion. 
From the larger portion (portio major) two main branches arise, 
ramus maxillaris superior and ramus mandibularis.. The smaller 
ganglion (portio minor) gives rise to ramus ophthalmieus. Besides 
these three main branches a much finer branch arises from the 
larger of these ganglionie enlargements, close to the root of nervus 
mandibularis and slightly anterior and ventral to it. It innervates 
muse. depressor palpebrae inferioris and, although much finer than 
the other three, is note-worthy because of the faet of the close 
connection which this branch brings about, by means of a fine 
connective fibre, between trigeminus and ramus palatinus VI. 
FIscHER describes this nerve, p. 119, but does not mention any con- 
nection with ramus palatinus, nor can I find mention of it any- 
where.) 
1. Ramus ophthalmicus is the smallest of the three main 
branches of nervus trigeminus. It arises from the anterior end 
of the smaller median portion of the Gasserian ganglion and takes 
its course anterior close to the membranous wall of the brain cavity, 
medial to the columella, and covered from the outer side by the 
thick mass of the temporal museles. When the nerve enters the 
orbit, it lies median to the bulbus oculi and dorsal to the origins 
of mm. rectus superior and obliquus superior. In the orbital region 
nervus ophthalmieus lies ventral and parallel to nervus trochlearis. 
Following the eurve of the orbit it approaches the interorbital sep- 
tum dorsal to the origin of m. obliquus inferior and from this point 
follows the septum narium direetly anterior, dorsal to nervus olfac- 
torius, to the anterior end of nasal region. The main branches 
given off in this course are as follows: 
A. Ramus frontalis arises dorsally, almost immediately after the 
