120 



opening into it anteriorly, and thirty-nine tubules springing from it as 

 it proceeds backwards. The anterior part of the hyomandibular canal, 

 the ventral loop and the dorsal extension are all supplied with bran- 

 ches from the hyomandibular nerve , some of which leave the nerve 

 bçfore it enters the large hyomandibular group of ampullae; while 

 others leave the nerve after it enters the ampullary capsule. Exclusive 

 of the loop, there are about twenty branches reaching the ventral part 

 of the canal, and over fifty the dorsal extension. 



The mandibular portion of the hyomandibular canal is not in 

 connection with the horizontal part ; but the two mandibular portions 

 meet and blend in the middle line. From the mandibular commissure 

 thirty-nine tubules spring; and each half receives thirteen branches 

 from the mandibular branch of the hyomandibular nerve. 



The lateral canal consists of the trunk, commissural and precom- 

 missural portions. The precommissural portion continuous with the 

 infra-orbital, runs back to the outer end of the temporal commissure ; 

 the commissural portions run inwards behind the auditory pores , to 

 meet and blend in the middle line , the trunk portion runs backwards 

 from the end of the commissure to the end of the vertebral column, 

 giving off two branches — a scapular and a post-scapular — on the 

 way. 



The precommissural and commissural portions give off no tubules, 

 the trunk portion in front of the scapular branch gives off eleven tubu- 

 les, and behind the post-scapular offshoot tubules are regularly given off 

 from the canal as it proceeds backwards — one for each segment. 

 Twenty-six tubules spring from the scapular branch, and twenty from 

 the post-scapular branch of the trunk canal. The precommissural, com- 

 missural and the part of the trunk canal in front of the shoulder girdle 

 are supplied by a special branch which springs from the lateralis nerve 

 immediately beyond its ganglion. Two branches spring from the late- 

 ralis in the region of the shoulder girdle , to supply the scapular and 

 post-scapular offshoots , and the part of the main canal in the vicinity 

 of their origin. Thirty twigs enter the scapular and twenty-four the 

 post-scapular branches of the main canal. The trunk canal, as it pro- 

 ceeds backwards from the region of the shoulder girdle, is perforated 

 by a branch from the lateralis nerve opposite each of the tubules by 

 which it opens to the exterior , the length of the nerves gradually di- 

 minishing from before backwards. 



The paper concludes with a short account of the histology of the 

 sensory canals, and of their sense organs I nerve hillocks) , and a short 

 reference to the sensory follicles — the spalt- papillon discovered by 

 Fritsch. 



