CRANIAL NERVES OF CHIMERA MONSTROSA. 639 



accompanies the profundus, though I think everyone would hesitate to say that the 

 fourth nerve was a branch of the profundus." To the objection that this is rather a 

 strained explanation of an awkward fact, I would reply; (1) That whilst it must be 

 considered an undoubted fact that the profundus of Chimsera does innervate sense organs 

 of the lateral line, yet it is the only case of such innervation, and probably the only 

 authentic case of any such innervation from the Vth ; (2) That having in view the 

 wealth of evidence in favour of the above view of the lateral line system, one is entitled 

 to take refuge behind the statement, that until satisfactory histological evidence is 

 produced proving the identity of the fibres from the profundus to lateral sense organs 

 with the trigeminal nerve, we may justly decline to believe that such identity exists.* 



The other case is more difficult of explanation, and must, I fear, be permitted to 

 stand over for the present, pending further investigation on the lines followed by Strong. 

 It is that the glossopharyngeal may innervate a portion of the lateral line system. This 

 is known to obtain in Elasmobranchs (Mustelus, Eamsay- Wright, 34 ; Lcemargus, 

 Ewart and Cole, 66), Teleosts (Pollard, 60), and Ganoids (Allis, 49). I have failed 

 to find it myself in Chimsera, and it is significant that Strong failed to demonstrate it 

 in Amphibia. On the other hand, its almost constant occurrence in Teleosts is perplexing, 

 and Pollard found the dorsal branch of the IXth supplying a single sense organ in 

 many Siluroids, and further, that this sense organ was homologous throughout all the 

 forms examined. Pollard's statements, taken together with the occurrence of this 

 nerve in such divergent groups, seem to be fatal to any such explanation as that 

 applied to the case of the profundus, and speculation is idle pending the production of 

 microscopic evidence as to the origin and course of the lateral line fibres in the dorsal 

 branch of the IXth in Teleostei. 



The only case in which the origin of a dorsal branch of the glossopharyngeal supply- 

 ing lateral sense organs has been carefully studied is that of Amia, in which some very 

 remarkable facts, entirely supporting the view of the lateral line system advocated in 

 the present communication, have been discovered by Allis (49). Allis finds that the 

 dorsal branch of the glossopharyngeal of Amia arises by a separate root from the brain, 

 passes through a separate foramen in the skull, and has a separate ganglion more or 

 less distinct from the ganglion on the glossopharyngeal. The dorsal branch of Amia, 

 therefore, is exactly comparable to the other four divisions of the lateral line system, 

 each of which in the typical condition arises by a separate root. I strongly suspect 

 that further investigation will result in disassociating a portion of this nerve (where it 

 innervates a part of the lateral line system) from the IXth, and placing it with the 

 other lateral line nerves. A study of its internal origin in Amia would go a long way 

 towards settling the question. 



It only remains now to consider the system of classification adopted by Garman (44). 

 Garman did not devote special attention to the innervation of the canals, and hence his 

 nomenclature has a geographical value only. This is illustrated by the fact that in 



* This question is further discussed on p. 649. 

 VOL. XXXVIII. PART III. (NO. 19). 4 U 



