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the facial and vagus. The supra-orbital, infra-orbital and hyo-mandi- 

 bular are related to the ophthalmic, buccal, and hyo-mandibular divi- 

 sions of the facial, respectively, while the lateral is related to the 

 lateralis division of the vagus. 



In Laemargus the supra-orbital canal, beginning a short distance 

 in front of the auditory pore , runs forwards above the eye and after 

 penetrating the snout , and again returning to the dorsal surface to 

 extend over the nasal capsule, it runs backwards under the head, to 

 end by opening into the infra-orbital canal. It lies in, immediately 

 under , or from 3 to 6 mm below the skin ; is innervated by eighty 

 branches from the superficial ophthalmic division of the facial, and 

 opens on the surface of the skin by eighty-one short, slender tubules. 



The infra-orbital canal , beginning in connection with the supra- 

 orbital, runs outwards and forwards, first behind and then below the 

 eye, and proceeds to the ventral surface, where after communicating 

 with the supra-orbital and hyo-mandibular canals, it bends inwards 

 towards the middle line. After forming a loop behind the nasal cap- 

 sule, it communicates with the infra-orbital canal of the opposite side, 

 and then on leaving its fellow, runs forwards to end blindly at the tip 

 of the snout. This canal, which in some parts lies at a deeper level 

 than the supra-orbital is innervated by eighty-seven branches from 

 the buccal division of the facial , and opens on the surface by eighty- 

 four tubules. 



The buccal nerve also supplies about two and a half centimetres 

 of the great longitudinal canal of the head and trunk. This short por- 

 tion I have described as an accessory (otic) part of the infra-orbital 

 canal, notwithstanding the fact that , instead of being continuous with 

 the infra-orbital , it is continuous with the lateral canal. The otic 

 portion begins one centimetre behind the terminal pore common to 

 the supra-orbital and infra- orbital canals, and arches outwards and 

 backwards. It is innervated by four twigs from a special (otic) branch 

 of the buccal, and opens on the surface by four tubules. 



The hyo-mandibular canal, very imcomplete in Laemargus, occu- 

 pies a nearly horizontal position at the side of the mouth. It commu- 

 nicates by its anterior end with the infra-orbital canal, and by its 

 posterior end opens through the skin, and it receives eighteen bran- 

 ches from the hyo-mandibular nerve and gives off eighteen tubules. 



The lateral canal I have described as consisting of three portions, 

 1) the trunk, 2) the commissural, and 3) the precommissural portions. 

 The short precommissural part extends from the otic portion of the 

 infra-orbital to the beginning of the temporal commissure ; the commis- 

 sural portion which runs inwards behind the auditory pore, meets and 



