HUDSANSEORGANENE HOS SPINAX NIGER, BONAPARTE 351 



rent branches of the sensory canals are marked as on my own 

 textfigures. The index letters are as on Ewarts diagram. 



Fa^., Four roots, the fibres ot which are rearranged to form the three 

 supra-branchial branches of the facial the superficial ophthalmic, 

 buccal, and hyomandibular), Avhich innervates the five groups of 

 ampullae, and the supra-orbital, infra-orbital, and hyomandibular 

 sensory canals. 



s.o.f., The first dorsal branch of facial — the ophthalmicus superficialis — 

 which supplies the supra-orbital canal (S.O.) the superf. ophthalmic 

 group of ampullæ {S.O. A.), s.of.^. Ihe gangtion; so.f.'^, the ventral 

 branch passing to the terminal portion of the supra-orbital canal 

 (S.O.). 

 bu-, The second dorsal branch of facial — the buccalis — which sup- 

 plies the infra-orbital canal (I.O.), and the inner (LB. A.) and outer 

 (O.B.A.) buccal groups of ampullae, bu., the ganglion on the buccal 

 nerve, from which a branch springs to supply the proxinal part of 

 the infra-orbital canal; 6m.', the inner division of the buccal which 

 supplies part of the infra-orbital canal and the outer buccal group 

 of ampullæ (O.B.A.); hm., the third dorsal branch of facial — hyo- 

 mandibularis — which innervates the hyoid and mandibular groups 

 of ampullæ, and the hyomandibular canal, including the ventral 

 loop, the dorsal extension, and the mandibular part, when present ;^ 

 hg., the ganglion of the hyomandibular lying in contact with the 

 ganglion of the facial proper (fa); hm.^, the large branch for the 

 hyoid group (HA.) of ampullæ; hm.^, the branch which supplies 

 the mandibular group of ampullæ (M. A.) and the mandibular canal 

 (m.c) — the mandibular offshott and the mandibular group of 

 ampullæ are both absent in Læmargus; sp, spiracle. 

 Au., The auditory nerve passing to the auditory apparatus (A.A.). 

 a., auditorjr pore; Gl., glossopharyngeal nerve arising under cover 

 of the lateralis; gl., its ganglion, beyond which are the pharyngeal 

 pre-and post-branchial branches; gl., the dorsal branch represented 

 as supplying 1) a short segment (T.T.) of the great longi tudinal 

 canal immediately behind the infra-orbital canal, and 2) a row of 

 pitorgans (p o.). That the dorsal branch of the glossopharyngeal 

 innervates sense organs and pit organs in Selachian as in Amia 

 has not yet been demonstrated. 

 La., Lateralis nerve; Ig., lateralis ganglion; l.^, first branch passing to 

 the temporal commissure (L.c) and the anterior part of the lateral 

 canal (L); l.^, branch springing from the ganglion to supply part 

 of the canal and anterior follicles or pit organs (p.o.l): l.n., the 

 lateralis extending backwards, nearly parallel with the lateral 

 canal (L). 

 Ibr-obr., First — fifth branchial clefts. 



