MOTOR NUCLEI IN PHYLOGENY 87 



buds in crocodilians. In the latter forms taste buds are said 

 to occur only on the dorsal part of the mouth near the choanae 

 and around the entrance of pharynx (Bath, 3) . In correspond- 

 ence with these peripheral conditions, the VII-IX motor nucleus 

 is most caudally situated in chelonians (Damonia and Chelone) 

 and most rostrally placed in AlUgator. 



The association of the motor VII-IX nuclei in reptiles to form 

 a singe cell complex is one of the most striking peculiarities of 

 the motor nuclear pattern of these forms. A similar motor 

 VII-IX nuclear association has been observed in such widely 

 dissociated forms as Lophius and Canis, but in no vertebrate 

 class other than reptiles does this condition obtain as a group 

 character. It follows, therefore, that in each of the various 

 reptilian orders some fundamentally similar reflex mechanism 

 must exist whose common efferent path consists of VII-IX 

 neurones. 



It will be of interest to inquire whether or not there be any 

 constant feature in the peripheral distribution of the motor VII 

 and IX nerves which may suggest some reason for the central 

 association of their motor perikaryons. Among reptiles it may 

 be broadly stated that the VII motor nerve is distributed pe- 

 ripherally to three muscles, viz., m. depressor mandibulae, m. 

 sphincter colli, and m. intermandibularis in its caudal part.' 

 On the other hand, the motor IX peripheral distribution in 

 reptiles would appear to be somewhat variable. In Anolis 

 Willard (1. c.) has called attention to the fact that the laryngeal 

 muscles may be innervated from IX, from X, or from both 

 these nerves. Goppert (21) considers that the R. recurrens 

 vagi alone supplies the laryngeal muscles of reptiles. Hoffmann 

 (1. c.) describes the muscles of the larynx as innervated by the 

 IX in chelonians where this nerve is also distributed to the m. 

 cerato-maxillaris and in crocodilians to 'pharyngeal muscles.' 

 Thus, among reptiles it may be said that while the peripheral 



^ This nomenclature has been somewhat arbitrarily selected from the host of 

 synonyms by which these muscles have been known because it appears to be 

 most generallj^ descriptive of the muscles in question (Adams, 1; Willard, 43; 

 Hoffmann, 26; Edgeworth, 13; Watkinson, 42; Fatamura, 14; Bradley, 7, et al.). 



