224 EDWAKP PHELPS ALI-tS, JUN. 



Troclilearis und die Portio trigemini rami ophtlialmici super- 

 ficialis eiii und derselbe Nerv ist." While it is evidently 

 unfair to Hoffmann to quote these several statements apart 

 from liis general discussion of the subject, I must confess 

 to being unable to form a clear idea either of the relation- 

 ships of the nerves here concerned, or of their manner of 

 development. If the portio minor s. trigemini is a branch 

 of the ramus ophthalmicus profundus, it is evidently the 

 homologue of the portio ophtlialmici profundi of Amia, as 

 I am seeking to establish. If it arises as a branch of a 

 nerve complex that is wholly separate and independent of 

 the nervus profundus, it would seem as if it could not be 

 the homologue of the nerve of Amia, and it may be that 

 serially homologous branches of two independent nerves — the 

 trigeminus and profundus — are here concerned, the two 

 branches being found separate and distinct in the two branches 

 of Lasmargus just above referred to. The so-called thalamic 

 nerve of Hoffmann's descriptions, the nerve marked X in 

 certain of his figures (34, fig. 38), may then be one of these 

 two bi'anches. 



In Squalus Acanthias Neal says (45, p. 238) that the fibres 

 that form the rami ophthalmicus superficialis and ophthal- 

 micus profundus trigemini arise from the posterior root or 

 portio major of the urigeminus. This so-called posterior 

 trigeminus root (portio major) is simply a part of the anterior 

 trigeminus root of Haller's nomenclature, and as the anterior 

 root (portio minor) of NeaPs descriptions is said by him to be 

 largely motor, and destined entirely to the mandibular arch, 

 the posterior root must be the spinal fifth component of the 

 nervus. The ophthalmicus superficialis trigemini of this fish 

 is then evidently the homologue of the portio ophtlialmici 

 profundi of Aiiiia, and not of the portio trigemini of that 

 fish. Neal shows the nerve X of Hoffmann's descriptions in 

 one of his figures (fig. K, p. 234), but I do not find that 

 he describes it. 



As some slight further evidence of my conclusion that the 

 terminal-bud communis fibres that form the so-called ramus 



