NoRRlS, Nerves of Amphtuma. 541 



into a number of terminal branches, one of which anastomoses 

 with the mandibularis V as already noted. Ths other branches 

 supply the ventral lateral wall of the anterior floor of the mouth. 

 In this account the alveolaris is assumed to be a pretrematic 

 nerve. 



h. The rami rnentalis externus and internus VII. — From the 

 hyomandibular trunk of the facial nerve there are given off two 

 large lateral Hne rami, of which the anterior dorsal one supplies 

 the angular and the oral series of neuromasts, and the posterior 

 ventral one the gular series of neuromasts. Kingsley designated 

 the first as r. mandibularis externus, and the second as r. hyoman- 

 dibularis accessorius. Each contains lateral line fibers onl}', and 

 the two evidently correspond to the two nerves which in other 

 Urodela hitherto figured arise by a common trunk from the 

 hyomandibularis, and which in Amblystoma are termed by Cog- 

 hill r. mentalis externus and r. mentalis internus. Fischer 

 seems to have overlooked the internal division in Amphiuma. 

 At a point about opposite the articulation of the lower jaw the r. 

 mentalis internus divides into two branches that pass anteriorly 

 parallel to each other. I find no anastomoses between the r. 

 mentalis internus and the r. mandibularis V, such as Kingsley 

 reports, much less can I substantiate the statements of Druner 

 that numerous anastomoses occur between these nerves. 



At the point where the r. me ntahs externus leaves the hyomandib- 

 ular trunk there are given off a few small nerves (figured as two 

 in number in the illustrations), partly from the main nerve and 

 partly from the mentalis externus, which supply the post-orbital 

 and jugular series of neuromasts. These small lateralis branches 

 have a very wide distribution for their size. Some of their smaller 

 divisions may be traced through hundreds of sections, yet consist 

 of but two or three fibers each. In their origin and distribution 

 these small lateralis nerves seem to represent opercular branches 

 of fishes. Druner reports a small cutaneous branch given off 

 from the mentalis externus and passing to the skin overlying the 

 depressor mandibulae muscle. I fail to find such a nerve. More- 

 over the occurrence of general cutaneous fibers in a branch of 

 the seventh nerve before the anastomosis X ad VII is received 

 is improbable. I do find a small branch of lateralis fibers leaving 

 the r. mentalis internus and supplying the posterior neuromasts of 

 the gular series overlying the depressor mandibulae muscle. 



