,972 MRS. O. A. MERRITT UAWKES ON THE [Dec. 11, 



•Se- 

 this branch he considers " would correspond to the ramus ophthal- 

 micus sujDerficialis Y. of Selachians" (15. p. 157). This being the 

 case, the profundus of Petromyzon combines the conditions found 

 both in Chimcera and Amia. Perhaps microscopical work would 

 show some connection between these nerves in Ghlamydoselachus, 

 unless, indeed, the condition of the profundus is here more 

 primitive even than in Petromyzon. 



The anastomosing branch (Plate LXIX. fig. 4) between the 

 profundus and oculo-motor nerves, mentioned above, is interesting 

 in its relation to the theory that the latter is the motor repre- 

 sentative of the primitive profundus nerve, for it may represent 

 a connection which originally existed between these two nerves. 

 But if this relationship does not exist, what may this connection 

 signify ? May it not be suggested that, as the radix brevis has 

 not been found and may not be pi'esent, this connection between 

 the profundus and oculo-motor nerves represents the fibres which 

 connect the ciliaiy ganglion and the oculo-motor nerve, which 

 here pass not directly to the ciliary ganglion, but by way of the 

 profundus nerve ? 



(d) The superjicicd oplitludmic V. passes from the Gasserian 

 ganglion side by side with the profundus nerve, which it equals 

 in size. It at once passes dorsally and enters the same groove as 

 the superficialis VII., with which, however, it does not unite. 

 About as far forward as the external nares, but nearer the median 

 line, it spreads out into many branches, which lie immediately 

 under the skin. This nerve apj^arently contains only cutaneous 

 elements, and hence has "the primary composition of this nerve" 

 (13. p. 365). The condition of the s. ophthalmic V. in CJdamydo- 

 selachus is similar to that found by Cole and Dakin (4) in one 

 specimen of Chimcera, where the ophthalmicus superficialis tri- 

 gemini was in no way connected with the ophthalmic VII., and 

 arose " from the main trunk of the trigeminus." 



II. The Facicdis Nerve. 



The Facialis is made up in Chlamydoselachus, as in all fishes, of 

 two distinct and yet united parts, the lateralis element and the 

 usual factors of a branchiomeric nerve ; of these parts the former 

 is the more obvious, for the branchiomeric branches are of com- 

 paratively inconsiderable proportions. The anterior part of the 

 Facialis, which consists of the buccal ganglion and of two nerves, 

 the ramus superficialis ophthalmicus facialis and the ramus buc- 

 calis, is entirely lateralis. The posterior portion of the Facialis 

 consists of the truncus hyomandibularis, which contains a large 

 lateralis element as well as parts of a branchiomei'ic nerve. 



The buccalis ganglion (Plate LXVIII. figs. 2 & 3), which over- 

 lies and is partly united to the Gasserian ganglion, arises by two 

 roots of approximately equal diameter : of these one (A) is more 

 anterior and somewhat moi'e dorsal in position and also longer 

 than the other (B), which arises just above the roots of the 



