26 F. L. LANDACRE 
peripheral point of distribution, which is to the skin at a point 
ventral to the point of entrance of the olfactory nerve into the 
brain wall. All these run to the ectoderm. The size of this 
nerve in the specimen plotted as compared with the r. oph. sup. 
V is much more like the 18 mm. embryo plotted by Seammon 
(11) than the 20 mm. embryo plotted by the same author. In 
the 20 mm. embryo plotted by Scammon the r. oph. sup. V is 
much longer than the r. oph. prof. V. 
4. THE GASSERIAN GANGLION 
The Gasserian ganglion (figs. 1 and 3, G.Gass.) is very large 
and lies just posterior to the dorsal half of the eye. It is placed 
diagonally in the head with its long axis nearly in the trans- 
verse plane but with its proximal end slightly anterior to its 
distal end. It extends ventrally and slightly caudad from its 
proximal end so that its distal end lies at the level of the dorsal 
border of the lens. It comes into contact on its dorsal and an- 
terior surface with the root of the profundus ganglion and on 
its ventral and lateral surface with the dorsal lateralis ganglon 
of VII. On its mesial surface it comes into contact with the m. 
rectus externus of the eye. Viewed from the lateral surface the 
ganglion is partly concealed by the dorsal lateralis ganglion of 
VII and by the r. oph. sup. VII and r. buccalis VII. 
The ganglion is forked at its distal extremity where the two 
chief rami arise, but its form is not modified by the exit of the 
r. oph. sup. V. It is of nearly uniform thickness throughout’ | 
its length. Excepting the two small roots entering with the 
portio minor mentioned above, the fibers passing proximally 
from this ganglion form a single compact and relatively massive 
root whose fibers pass into the spinal V tract. 
5. RAMUS OPHTHALMICUS SUPERFICIALIS V 
Of the three rami arising from the Gasserian ganglion at this 
stage, the most anterior one, the r. oph. sup. V (figs. 1 and 2, 
R.O.S.V.), is much the smallest. It arises on the anterior sur- 
face of the proximal end of the ganglion slightly dorsal and 
