88 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
R. HYPOGLOSSAL NERVE. 
The twelfth cranial nerve is well developed in Anolis, in correlation 
with the condition of the tongue and especially with its muscular 
tongue papillae. It arises from three distinct roots and, with the 
exception of the brief union with the pharyngo-laryngeal ramus of 1X 
and X, takes an independent course to the tongue, where the greater 
part of its fibers are distributed to the intrinsic musculature. A few 
small bundles are given off to the cerato-mandibularis group as it 
crosses these muscles. Not all the hypoglossal nerve is distributed 
to the ventral region, a part of the last (third) root retaining the dorsal 
and lateral rami of the spinal nerve from which it phylogenetically has 
arisen. These go to the cervical muscles. 
Roots of the hypoglossal. Although nerve XII is a combination of 
roots which emerge from the cranium through three separate foramina, 
there is no separation of root bundles at their origin into three groups. 
They form a continuous series along the somatic motor line, and a 
comparison shows that they may be differently combined to emerge 
from the cranium. ‘There is, however, one feature which is constant, 
viz., the presence of a cervical part on the last root of the series, which 
is marked off from the hypoglossal part by a difference in the size of 
its fibers, thus showing a correlation between its functions (as indi- 
cated by its distribution) and the structure of its fibers. Special 
series of sections prepared for the purpose of tracing these differences 
to central nuclei have thus far failed, owing to the difficulty of carrying 
them through the meninges of the brain. Where the root bundles 
pass through the foramina the fibers are well preserved and here the 
two kinds of fibers are distinctly segregated and were easily followed 
into their respective rami. 
Distribution of the cervical part (Plates 2, 3, figs. 4-6). The cervi- 
cal part is made up of larger fibers than those forming the hypo- 
glossal nerve proper. They equal in caliber the motor components of 
the first and second spinal nerves, and their distribution is similar. 
The hypoglossal bundle in the posterior root of XII is in every way 
like the other roots of this nerve which join it to form the main hypo- | 
glossal trunk. The cervical portion, having a dorsal position in the | 
common root as it emerges from. the foramen, divides at once into a 
lateral (crv. l. XII) and a dorsal (crv. d. XII) ramus. ‘The lateral 
ramus is the larger and is distributed to the. spinalis colli muscle 
(Plate 7, fig. 23, spr. coll.). The dorsal ramus passes caudad on the 
