willard: cranial nerves of anolis carolinensis. 45 



K. TROCHLEAR NERVE. 



Xerve IV (Plate 2, fig. 4, /I'), from its nucleus of origin on the side 

 of the aqueduct floor opposite to that of its emergence, passes dorsad 

 of the mesocoele directly to the surface, the whole central course 

 showing in a single transverse section. Peripherally it turns cephalad 

 for a short intracranial course, lying between the brain and the Gas- 

 serian ganglion. It then passes through the membranous cranivim, 

 but keeps a median position throughout its course, to the dorsal oblique 

 muscle, which receives all of its fibers (Plates 5, 6, figs. 12-17). 



L. ABDUCENT NERVE. 



The central origin of nerve VI (Plate 2, fig. 4, F/) in the meten- 

 cephalon was readily found. The neuraxons leave this part of the 

 brain in small groups as large heavily medullated fibers. These 

 emerge from the ventral side of the brain in small rootlets, which 

 immediately combine into one main trunk. After a short intra- 

 cranial course nerve VI enters the sphenoid bone and takes a 

 course cephalad through a special foramen between the outer and 

 inner lamellae of this bone, and dorsal 'to the beginnings of the basi- 

 pterygoid process of the sphenoid (Plate 6, fig. 17). This foramen 

 opens mesally into the bony pocket protecting the ventral end of the 

 pituitary body and at the point of origin of the bursalis and retractor 

 oculi muscles. Nerve VI passes through these muscles to reach the 

 posterior rectus, which it innervates (Plate 5, 6, figs. 15, 16). The 

 bursalis and retractor oculi muscles are innervated by a small ramus of 

 not more than 25 fibers which is given off from VI as it passes between 

 them. This is shown in Plate 6, fig. 16 (brs.), but in the plotting 

 (Plate 2, fig. 4) it is covered by the main trunk. It is difficult to 

 explain the very pronoimced disproportion between this small ramus 

 and the remainder of the abducent nerve. No connection was found 

 which would relate the abducent nerve to any structures other than 

 the three muscles named. 



Ciliary Ganglion and Nerves. 



In their macroscopic features the ciliary nerves and ganglion and 

 their relation to the trigeminal and oculo motor nerves are compara- 



