84 bulletin: museum of comparative zoology. 



almost immediately and the lungs are very richly supplied. The 

 branches to tlie heart did not appear. 



Ramus recurrens laryngis X (Plate 2, fig. 5; rcr. X.). The course 

 of this ramus is directly cephalad to the larynx, following along the 

 lateral side of trachea to reach it. Numerous very fine branches are 

 given off in its course (not shown in Plate 2, fig. 5). Reaching the 

 larjTix this nerve breaks up, first dividing into the two main terminal 

 divisions shown in the figure. One of these lies on the dorso-lateral 

 side of the larynx and passes through a portion of the longitudinal 

 muscle to reach a more anterior position, where it innervates the 

 mucous mevibrcme just posterior to the glottis. The other branch, 

 the more iKedian one in the figure, innervates the mucous membrane 

 of the veiifJCr-lateral part of the larynx. The first branch in its pas- 

 sage through the muscle becomes closely involved in the motor com- 

 plex, and is separable from it only through the study of sections. 

 If it contributes motor fibers to this, it is only very slightly, and my 

 belief is that in Anolis the ramus recurrens is wholly sensory. Sec- 

 tion 659 (Plate 4, fig. 11) is anterior to the main branches so that no 

 part of the recurrent ramus appears. Some motor twigs are shown 

 in the muscle. 



More data are needed to homologize the branches of nerves IX and 

 X with those of Amphibia. In the latter the ramus recurrens X in- 

 nervates the muscles of the larynx (Coghill, :02, p. 245 ; Norris, :08, 

 p. 552). 



Through comparative anatomy Fischer arrived at conclusions which 

 conform with the facts as stated for Anolis. He found the intimate 

 mingling of the terminal twigs of the ramus recurrens X and the 

 pharyngo-laryngeus, so generally described in other forms, to be 

 absent in two cases, so that the distribution of the two nerves was 

 distinct, and in these cases the recurrent ramus is held to be sensory, 

 not motor. " Im den Fallen, wo der R. recurrens sich nicht mit jenem 

 [phar>^lgo-laryngeus] verbindet (Varanus Bengalensis, Platydactylus 

 guttatus) geht dieser [r. recurrens] nicht in die Muskeln, sondern an 

 die Schleimhaute des Kehlkopfes" (Fischer '52, p. 48). But Watkin- 

 son ( :06, p. 467) for another species of Varanus states that the united 

 fibers of the ramus recurrens X and the terminal branches of IX 

 are distributed to the muscles of the larynx. Her observation was not 

 properly supported, however, in regard to either point, as in her 

 species (1) nerve IX previously received fibers from X, as in Anolis, 

 and (2) a mere union of rami as demonstrated in dissection does not 

 in itself prove similarity of distribution. 



