willard: cranial nerves of anolis carolinensis. 97 



tiles: (1) the persistence of three occipital foramina, and (2) the mixed 

 spinal and hypoglossal character of its third root. The latter condi- 

 tion is not described for any other lizard. There is practically no 

 union of the hypoglossal part of the last root of XII with the first 

 spinal nerve, a condition which is described by Fischer as general. If 

 we imagine the cephalization process to progress further in Anolis, we 

 should expect roots one and two of XII to merge with each other, the 

 spinal or cervical part of root three to disappear and the first spinal 

 nerve to be drawn more into the field occupied by it. This is practi- 

 cally what is represented (Fischer) in those forms where but two roots 

 have been described. Evidence from the embryological side (Van 

 Wijhe, '86, Van Bemmelen, '89, Hoffmann, '79-90) supports Fiir- 

 liringer's ('97) generalization that the hypoglossal of reptiles repre- 

 sents three ventral spinal roots. 



The cervical plexus is represented in Anolis by the combination of 

 XII with the first spinal and the commissure between the second and 

 third spinal nerves. The ventral ramus of the first spinal is but 

 loosely associated, sometimes not at all, with XII. The only constant 

 connection, then, is that of the dorsal ramus of XII (cervicalis dorsalis 

 XII) with the same ramus of the first spinal (Fig. 6, crv. d. XII). 

 This anastomosis may be considered a remnant of the closer rela- 

 tion of these nerves ^A-hich existed before the rise of the tongue mus- 

 culature. 



Anolis agrees with the typical condition of reptiles in the absence of a 

 sensory component in the first and second spinal nerves. Fischer's 

 reference to the exceptional occurrence of a dorsal root for the second 

 spinal is not carried farther in his descriptions. Rabl-Riickhard 

 ('78, p. 342) states that in the alligator the third is the first of the spinal 

 nerves to possess a sensory part, but in contrast to the lizards (Anolis) 

 the third and fourth spinal nerves also have (Fischer) greatly reduced 

 dorsal roots, indicating a less sensitive integument in the alligator. 

 It will be seen that in Anolis the field innervated by the sensory com- 

 ponents of the third spinal nerve extends far cephalad both on the 

 dorsal and ventral sides, thus demanding a strong dorsal root. 



In regard to the second point in the comparison, i.e., the differentia- 

 tion of the nerve itself, we have to deal with a histological problem 

 which cannot be profitably discussed without a complete knowledge of 

 the histological elements involved. The fixation of my material is 

 not uniform enough in all parts to admit of a detailed comparison of the 

 caliber of the medullated fibers as found in different nerves. How- 

 ever, in Anolis the difference in the fibers of XII, as compared with 



