WILLARD: CRANIAL NERVES OF ANOLIS CAROLINENSIS. 89 
dorsal side of this muscle to join the dorsal ramus of the first spinal 
nerve, with which its terminal fibers become mingled (Plate 3, fig. 6, 
spi.d.1). Itis anticipated that, upon careful study of the brain with 
reference to the nucleus of XII, some difference in origin of these two 
bundles (crv. 1. XIJ and crv. d. XII) as compared with XII proper, 
will be demonstrable. 
In its course around the pharynx to reach the ventral side of the 
neck XII crosses dorsad of the thymus gland (Plate 7, fig. 24, gl. thy.), 
and also of the visceral ramus of X and the sympathetic trunk, which 
lie close together on the dorsal side of this gland (Plates 2, 3, figs. 
4,6,and 7, vsc. X and sy.). XII, turning ventrally, passes between the 
thymus gland and the jugular vein mesad of all muscles. Section 
1595 (Plate 7, fig. 24) falls in a plane just caudad of XII so that no 
part of it appears; the other structures referred to show well in this 
section. Section 1480 (Plate 7, fig. 23) shows XII after it has attained 
its ventral position. ‘This is reached by crossing the end of the first 
cerato-branchial on its lateral side. Nerve XII then takes a direction , 
cephalad (Plate 7, figs. 22, 23) between the cerato-hyal (ker-hy.) and 
the first cerato-branchial (ker-brn. I), on the ventral side of the 
cerato-hyoideus (hyo-glossus) muscle. Its direction from this point 
onward is cephalad and mesad along the lateral edge of the genio- 
glossus muscle and the median side of the cerato-hyal. As it passes 
| forward it comes to lie on the ventral side of the genio-glossus (gen-gls.), 
where it parallels the mandible to a point as far forward as the basi- 
hyal (Plate 6, figs. 16-18). Here we find a division of the main 
trunk into two rami of about equal size. The median one immediately 
| divides, so we then have a three-fold division (Plate 5, fig. 12, Ing. I. 
AIT, Ing. ?m. XII, and Ing. m. XIT) of the main trunk, the lateral one 
‘containing about half the fibers. From this point forward these 
three main rami diverge and pass up into the tongue musculature for 
distribution (Plate 2, fig.5). This course of the main trunk and termi- 
nal divisions of XII has been described without reference as yet to 
certain small rami which it gives off. The branches of XII will now 
be described in more detail: 
Distribution of the hypoglossal nerve. (a) Ramus pharyngo-laryngeus 
(pha-lar’.). Although r. pharyngo-laryngeus is given off as a branch’ 
x XU, the principal, if not the sole, source of its fibers is from nerves 
{X and X, as described in connection with the account of those nerves. 
| (b). Between (a) and the main divisions of XII there are given 
vf several very small rami, which innervate the muscles between 
vhich the hypoglossal nerve passes. The first of these (Plate 2, fig. 5, 
XII") supplies the cerato-mandibularis 1 (Fig. 18) in its posterior 
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