197 



the supra-orbital line is absent. But however this may be, the nerve 

 certainly is not the ophthalmicus superficialis. That it is the buccal 

 seems to be implied by Miss Alcock's "third nerve", which leaves the 

 facial close to the "ophthalmicus superficialis" and undoubtedly seems 

 to correspond to the otic branch of the buccal of other Fishes. On 

 the other hand Miss Alcock's "fourth nerve" is suspiciously like the 

 true superficial ophthalmic — indeed the condition in Ammocoetes is 

 extraordinarily like what it is in some other Fishes. In fact still 

 assuming that the organs supplied by the facial are lateral organs, 

 this nerve presents no essential differences from the facial of other 

 Fishes, whilst the points of resemblance are most striking. Whilst I 

 am certain that Miss Alcock has confused end-buds with lateral sense 

 organs (and I know from experience how difficult it is to distinguish 

 these in early stages and even in young adults), it seems to me very 

 probable, taking Leydig's work into consideration, that the facial sense 

 organs are true lateral organs, and possibly also are some of the 

 dorsal IXth and Xth organs. 



On p. 44 et seq. ventral branches of the IXth and of each bran- 

 chial division of the vagus are described as innervating a row of sense 

 organs near the mid-ventral line. These nerves are so unlike any lateral 

 line nerves found in any other Fish that I think most authors would 

 have hesitated before asserting that the organs they supplied were 

 true lateral sense organs. Miss Alcock indeed does recognise this fact, 

 but that does not prevent her at once assuming that the pits are lateral 

 organs, and the nerves supplying them lateral line nerves. What we 

 want here is observation and not assumption — epecially as proof of 

 Miss Alcock's statements might almost cause the whole question of 

 the lateral line organs to be again reconsidered. 



The only other point with regard to the vagus is with respect to 

 the so-called lateralis nerve. In my Linnean Society paper I have 

 followed Dr. Strong in believing that this nerve is not a lateral line 

 nerve, but belongs to the lateralis accessorius system. Miss Alcock 

 on the other hand considers it to be a lateral line nerve, although 

 she admits that she has no reason for believing it to be such — an 

 admission which might also have been made with regard to the other 

 "lateral line nerves". She does not find any anastomosis with the 

 spinal nerves in the branchial region, which is not extraordinary seeing 

 that this does not obtain in most other Fishes. Such anastomosis how- 

 ever will, I think, be found to obtain behind the branchial region. If 

 I may make a suggestion, it would be as well if Miss Alcock were 

 to make a critical examination of the "lateralis" nerve, and also of 



Anat \nz. XV. Aulsatzc. 14 



