222 EDWARD PHELPS ALLIS, JUN. 



Theil des erster I'rigemiiius iiach rostralwarts waiiderte, 

 wahrend der R. ophthalmicus profundus^ fixirt durch seiiiun 

 gesoiiderten Austritt aus dein Cranium^ zuriickblieb uiid nun 

 mit dem zweiten Trigeminus vom Centralorgan abgeht." It 

 seems much more probable that Haller has made some mistake 

 in homologising his fibre tracts, in addition to wholly over- 

 looking the true ramus profundus. 



Scyllium thus probably presents a portio major of the 

 ramus ophthalmicus superficialis, formed by two bundles of 

 fibres derived, the one from the lobus trigemini, and the other 

 from the tuberculum acusticum, and a large portio minor of 

 the same nerve, derived from the anterior root of the 

 trigemino-facial complex. These two nerves issue from the 

 skull by separate foramina (Schwalbe), l)ut soon unite to 

 form a single nerve. The portio minor is evidently the 

 homologue of the general sensory component of my descrip- 

 tions of Mustelus, and hence is what I am led to consider as 

 the portio ophthalmici profundi of the superficial nerve. It 

 is relatively very large in Scyllium, the true ramus profundus 

 being, according to Schwalbe's descriptions, correspondingly 

 small. The two components of the portio major are, according 

 to my conclusions, destined, the one to innervate the sensory 

 organs of the lateral canals, and the other the sensory organs 

 of the ampullas. The former is the homologue of the portio 

 facialis of the ophthalmic nerve of Amia, and the other the 

 homologue of the portio trigemini. Haller says that his 

 so-called profundus nerve is exclusively motor. This is too 

 manifestly an error to need discussion, but it well shows how 

 liable one is to error, in the present state of our knowledge 

 of the subject, if one limits one's attention entirely to the 

 central origin of a nerve. 



In Lasmargus the ramus ophthalmicus superficialis trigemini 

 of Ewart's descriptions is said by him to be found as a separate 

 slender nerve, Avhich springs either from the trunk of the 

 trigeminus, or from its mandibular branch. Of it Ewart 

 says (18, p. 76) that it "neither innervates sensory nor 

 ampullary canals. It may, however, supply some of the 



