MUfSTELUS LiEVIS. 



^1^ 



to sepai'ate them. This trigeminal ophthahnic iievve, thus 

 formed, is accordingly quite probably the homologue of the 

 portio 0]ilithalmici of Amia plus the ophthalmicus superficialis 

 trigemini of the same fish. " A very small r. profundus 

 V " is said by Herrick to be found in Menidia, being said to 

 be there represented by certain general cutaneous fibres that 

 accompany the radix ciliaris longa to the ciliary ganglion. 

 While I should certainly consider these general cutaneous 

 fibres as an integral part of the radix longa, and not as 

 representing a ramus ophthalmicus profundus, as will be later 

 more fully discussed, it is important here to notice that the 

 fibres are general cutaneous ones, this thus indirectly sup- 

 porting my conclusion that the portio ophthalmici profundi of 

 Amia, and that nerve alone, is the general cutaneous com- 

 ponent of the ophthalmic nerves of teleosts. 



In Polypterus both van Wijhe (66) and Pollard (51) 

 describe a portio ophthalmici profundi, and also a ramus 

 ophthalmicus profundus that has the position of a selachian 

 profundus; but, in marked distinction with Amia and J^epi- 

 dosteus, no portio trigemini of the ophthahnicus superficialis 

 is definitely given by van Wijhe, and Pollard says that he 

 wholly failed to find that nerve. There is thus in this fish, 

 as in Acipenser, an apparent absence of a communis com- 

 ponent in the superficial ophthalmic nerve. In Acipeuser 

 this apparent absence was accounted for under the assump- 

 tion that the dorsal one of the two so-called lateral sensory 

 roots of the fish, the Trigeminus II dorsalis of Goronowitsch, 

 is a somewhat modified connnunis root, and that it is con- 

 cerned in the innervation of the sensory organs of the 

 nerve-sacs, those organs being derived from terminal buds. 

 What the apparent absence of this component in Polypterus 

 is due to is not evident from existing descriptions of that 

 fish. 



Turning now to selachians. Mailer (28) has recently very 

 thoroughly investigated the central origin and composition of 

 the cranial nerves in Scyllium. In this fish this author says 

 that Trigeminus 11 is mainly, if not exclusively, sensory, and 



