NoRRis, Nen^es of Amphiuma. 533 



in all directions to supply the skin on the side of the head. The 

 main mandibular nerve on reaching the mandible enters a groove 

 on the dorsal side of the latter (fig. 5) and soon divides into two 

 branches. The ventral of these passes directly down through the 

 jaw between the dentary bone and Meckel's cartilage and on 

 emerging between the angulo-splenial and the dentary bones 

 divides anteriorly and posteriorly into branches that supply the 

 mm. intermandibularis (mylohyoideus anterior) anterior and pos- 

 terior and the skin of the ventral surface covering these muscles. 

 The dorsal division runs along in the groove above Meckel's 

 cartilage between the dentary and the angulo-splenial bones, and 

 soon divides into two branches. The larger of these, of darker 

 staining fibers {md (j*^)), occupies a canal in the dentary bone 

 (fig. 4) and in turn divides into two divisions. Small branches to 

 the skin pass out from the canal, but the two chief divisions (repre- 

 sented as one nerve in fig. i) do not emerge from the dentary until 

 well near the tipof the jawwheretheysupplythe skin. The smaller 

 hghter stained division of the ramus in the mandibular groove 

 {md (jb)) shifts mesally and ventrally from the larger division and 

 runs along dorsal to Meckel's cartilage in a groove between the 

 dentary and angulo-splenial bones (fig. 4). There unites with it 

 a branch of the r. alveolaris VII {alv. (4)), the combined nerve 

 passing anteriorly just ventral to the teeth and apparently supply- 

 ing the latter and possibly the lateral floor of the mouth. It may 

 be traced as far as the extreme anterior teeth and always in close 

 relation to the latter. An anastomosis between that part of the 

 mandibularis supplying the intermandibular muscles and the por- 

 tion of the r. jugularis VII innervating the interhyoideus muscle, 

 such as CoGHiLL describes in Amblystoma, I do not find in Am- 

 phiuma, but it is certain that the two nerves in question approach 

 very close to each other. Kingsley was inclined to believe that 

 branches of the ramus mandibularis in Amphiuma supply lateral 

 line sense-organs. I can state with certainty that no such relation- 

 ship exists. 



c. The ramus ophthahnicus profundus V. — The ramus ophthal- 

 micus profundus leaves the extreme anterior portion of the gas- 

 serian ganglion and after passing anteriorly and somewhat dorsally 

 into the region of the eye divides into a number of branches, of 

 which there may be said to be five that are fairly constant in their 

 occurrence and relationships. Of these the first given off, the 



