70 DAVIDSON BLACK 



It is probable that in Hatteria the origin of the motor IX root 

 is similar to that obtaining in other reptiles. The glossopha- 

 ryngeal motor root in this form arises by three fine rootlets close 

 behind and somewhat more ventrally placed than the acusticus 

 root (Gisi, 1. c, p. 179). Some of the fibers of this nerve are 

 said to arise in a small nuclear area ventral from the descending 

 acusticus root and would appear from the description to be 

 sensory in character. Other fibers of the IX nerve are described 

 as being evidently connected with the fasciculus longitudinalis 

 medialis, and these no doubt represent the motor component. 

 Gisi also observes that the motor VII nucleus, made up of numer- 

 ous groups of cells, extends caudally for a long distance in this 

 animal. 



A comparison of the reconstruction charts (figs. 11 and 12) 

 brings out the fact that among the reptiles examined the motor 

 VII-IX nuclear complex with reference to the exit level of the 

 motor VII root is most rostrally placed in Alligator and most 

 caudally situated in Damonia, Varanus, Boa, and Chelone, 

 occupying intermediate places, respectively, in a scale arranged 

 on this basis of comparison. Further, when compared as ta 

 their position with regard to the floor of the fourth ventricle, 

 the most dorsally situated complex is found in Alligator, Chelone, 

 Boa, Damonia, and Varanus following in the order named. 

 Finally, it is to be noted that a small ventral motor VII nucleus 

 is present in Alligator as well as a third cell group labeled in 

 figure 12, A, with a question mark (?) whose connection with 

 the motor VII root has not beer; fully established. These sub- 

 sidiary cell groups have not been observed in the other reptiles 

 examined, though a partial division of the motor VII-IX nucleus 

 into dorsal and ventral moieties is indicated in Varanus (Kappers, 

 31, p. 65). 



Nerve VI 



In Damonia the abducens nerve arises in an elongated and 

 somewhat diffusely arranged nucleus of large multipolar cells 

 lying in the reticular formation alongside the fasciculus longi- 

 tudinalis medialis and in intimate association with the fibrae 



