228 Journal of Comparative Neurology, 



the m. interhyoideus and the overlying skin. Its most anterior 

 fibers fuse with the terminal twig of the mandibular V as already 

 described. 



T]lc r. alveolaiis VII, composed wholly of communis fibers, 

 follows the posterior border of the suspensorium to the angle 

 of the jaw. Along this part of its course the r. alveolaris lies 

 mesially of the hyo-suspensorial ligament and anteriorly of the 

 deep pharyngeal evagination which rejDresents the embryonic 

 spiracular cleft. At the ventral end of the suspensorium the 

 nerve passes across the mesial side of the angle of the jaw and 

 enters its canal in the mandible. 



Sometime before the alveolaris emerges from this canal it 

 divides into two branches, one of which anastomoses with the 

 fourth cutaneous branch of the mandibular V, and continues 

 cephalad within the canal to the teeth and gums, while the other 

 passes out of the canal at about the transverse level of the in- 

 ternal nares, and passes inward to the epithelium of the floor of 

 the mouth. 



In some cases the r. alveolaris gives off a large branch near 

 the angle of the jaw. This branch enters a distinct canal in the 

 mandible and has a distribution similar to that of the main 

 nerve. 



Soon after leaving the hyomandibular trunk, the main 

 nerve receives fibers from the r. communicans IX + X ad VII. 

 This relation will be noticed further in connection with the latter 

 nerve. 



Facialis A. — As the hyomandibular trunk leaves the fora- 

 men there is given off from the communis component a small 

 twig which passes caudad closely compressed upon the ventral 

 side of the ganglion of the r. mentalis. From this point it con- 

 tinues latero-caudad, ventrally of the r. communicans IX + X 

 ad VII, to the region of the posterior extremity of the cerato- 

 hyal bar. Here it anastomoses with the r. pre-trematicus IX. 

 This nerve appears in but one of my specimens. It will be dis- 

 cussed in Part II as Facialis A. 



In two specimens I have found a second cluster leaving the 

 hyo-mandibular trunk just after its exit from the foramen. These 



