478 Proceedings of Royal Society of Edinhurgh. [sess. 
correspond to the dorsal branch of the IX. In all probability further 
investigation will show that the dorsal branch of the Yllth, by a 
process of splitting, has given rise in Elasmobranchs to five distinct 
branches, viz., auditory, superficial ophthalmic, buccal, hyoman- 
dibular, and a cutaneous branch, supplying the skin in front |of the 
auditory capsule. 
Fig. 2. — Spinal nerves of Raia dissected with 1" lens. Semi-diagram- 
matic. STc., skull; v.G., vertebral column; 6\c., spinal cord; d.r., dorsal 
root ; V.T., ventral root ; d.d., dorsal branch from dorsal root (dorsal-dorsal) ; 
v.d.^ dorsal branch from ventral root (ventral-dorsal) ; m.p., muscular plexus — 
enters muscle at about level of 20th spinal. This fig. represents the nerves 
somewhat spread out, but the dorsal roots are really applied to one another, 
so that the dorsal branches from the ventral root come up between the ganglia 
on the dorsal roots, and are in all cases closely applied to them. Hence, until 
dissected, they appear to arise from the dorsal roots. 
V. The Trigeminus . — The recognised dorsal branches of the Vth 
are the superficial ophthalmic and the profundus, which supply the 
