62 bulletin: museltni of comparative zoology. 



of the dentary bone, which carries the nerve. Through this opening 

 into its cavity the tooth receives its nerve and blood supply. The 

 innervation was not determined for the posterior teeth, the first fibers 

 given off from the alveolar nerve being farther forward, where a small 

 number (3 or 4) of fibers with distinct sheaths come off from the main 

 ramus and run forward within the alveolar cavity for some distance, 

 but eventually pass into the cavities of the teeth (Plate 4, fig. 9, 

 rm. de.). Where these fibers are given off they show a character 

 similar to the cutaneous sensory components, although they either 

 become less heavily myelinated or, what is more likely, their position 

 makes fixation defective, for they can -ft-ith difficulty be traced through 

 the communication into the pulp cavity of the tooth. 'It is not 

 improbable that here they do lose their myelin sheaths. It is notice- 

 able in the mature teeth that the dentinal tubules are particularly 

 large at the apex of the teeth. No nerve fibers could be followed, 

 however, as far as the odontoblasts underlying this region. 



This alveolar ramus is described b}' Watkinson (:06, p. 462) as 

 innervating the teeth through the "rami dentales." Such rami in 

 Anolis would consist of a few fibers given off at wide intervals, which 

 would be difficult to discover except by microscopic methods, even 

 though they were not entirely \\athin the bony part of the jaw. Xorris 

 ( :08, p. 522) referred the innervation of the teeth in Amphiuma to a 

 combined V and VII nerve which runs along the median side of the 

 mandible. This nerve corresponds to the main part of the chorda 

 tympani in Anolis, which after temporary union with the mandibular 

 nerve has separated from it, reappearing with a mixture of cutaneous 

 components, which are distributed \\dth it. Although many fine 

 fibers pass from this nerve along the base of the teeth to the epithelium 

 of the lingual gums, no connection was established with the. teeth 

 themselves. 



N. FACIAL NERVE. 



The roots of the facial nerve. Two roots can be demonstrated for 

 nerve VII, a lateral (motor) one and a dorsal (sensory) one. The 

 sensory passes out directly from the fasciculus solitarius (Plate 6, 

 fig. 18, rx. VII) as a strong bundle to emerge from the brain dorsal to, 

 but in contact with, the root of VIII. It passes around the anterior 

 side of this root, being entirely covered laterally by the large acoustic 

 ganglion. On the ventral side of the root of VIII the sensory root of 



