1906.] ANATOMY OF CENTROPHORUS CALCEUS. 879 



immediately under the supra-orbital ridge. Whether there is 

 any intei'change of nerve-fibres I cainiot say. 



The nerves, concerning the identity of the branches of which, 

 as usual, there is doubt, are the trigeminal and facial, and this 

 question of identity is complicated by the fact that the disposition 

 of the nerves is slightly different on the two sides of the head *. 

 The roots of the fifth and seventh nerves, in the first place, are 

 difl^erent on the two sides of the head. On the left side (PI. LXI. 

 fig. 16) t the nerves which I (very possibly incorrectly) term the 

 ophthalmicus superficialis (0. S. YII.), ophthalmicus profundus 

 (0. P. VII.), and palatine (P. VII.) of the seventh originate from 

 a distinct root which is the most anterior of the three giving rise 

 to all the bi'anches of the fifth and seventh nerves ; on the right 

 side (fig. 17) t this anterior root, distinct at its origin, is later 

 fused with the other two roots. On the left side again, the 

 ophthalmicus superficialis clearly arises from this anterior root, 

 but on the right it is bound up, for an inch or so, with the lai-ge 

 ophthalmic branch of the fifth (O.Y.), and hence appears to arise 

 from it. The ophthalmic of the fifth — a very conspicuous nerve — 

 on both sides entirely or mainly ai-ises from the second root of the 

 primai-y three. This large ophthalmic of the fifth runs along the 

 upper border of the orbit, and sooner or later is joined towards the 

 anterior limit of the orbit by the smaller ophthalmicus superficialis 

 of the seventh, and these (with the ophthalmicus profundus which 

 joins them about half-an-inch in front of the cerebral hemisphere, 

 aftei- pieicing the anterior cartilaginous wall of the orbit) ramify 

 over the skin on the dorsal surface of the snout, supplying the 

 mucous canals in the usual manner. 



The huge nerve which, like the fifth ophthalmic, appears to 

 arise mainly from the second root of the fifth and seventh nerves, 

 and which runs outwards in the floor of the orbit, I have termed 

 the superior maxillaiy of the fifth (palato-nasal is perhaps bettei'). 

 Anteriorly it divides into several branches supplying the ventral 

 surface of the snout, a,nd near its oi'igin- gives ofi" a small ei- nei've 

 which extends downwards at the back of the orbit and forks 

 into anterior and posterioi- bi-anches which I have respectively 

 named the inferior maxillary (I. M. V.) and mandibular (MN. V.) 

 of the fifth. This nerve is joined, on both sides of the head, by 

 a branch from the palatine (?) ; in addition to this, it gives off 

 anteriorly on the right side a small nerve (V.L.) which rvms 

 almost parallel to it : on the left, the same small nerve originates 

 independently from the large superior maxillary. The large size 



* As Prof. Hickson kindly pointed out to me, Colling-e has previously described, 

 in 1895, other instances of the asyiunietrical distribution of the fifth and seventh 

 cranial nerves in several Teleosts (" On the Unsymnietrical Distribution of the 

 Cranial Nerves of Fishes." Jour. Anat, Physiol, vol. xxix.). 



f It is almost needless to say that in the dissections represented by both figs. 16 & 17, 

 large masses of cartilage have been removed both in front of and behind the orbital 

 cavity in order to expose the nerves better, and the same remark applies to a large 

 mtiscle which lay in the floor of the orbit just anterior to the large vertical process 

 arising from the upper jaw. The auditory organs have of course also been removed. 



