220 EDWAUD PflELPS ALLIS, JUtJ. 



that it arises by two roots^ an upper one from the " lobus n. 

 trigemini," and a loAver one from the ventral portion of the 

 so-called outer sensory " Oblongatagebiet '' (p. 436). The 

 lobus trigemini is said by him to be simply an " Abschnitt '^ 

 of the outer sensory oblongatagebiet, and that part of the 

 latter " gebiet " from which the ventral root of Trigeminus II 

 arises, is said to be the homologue of the dorso-lateral tract 

 of Goronowitsch (p. 423). 



Kingsbury (40, p. 27), before the publication of Haller's 

 work, was led to conclude that the lobus trigemini of Acipenser 

 was the probable homologue of the similarly named structure 

 in sharks, and, moreover, that further investigation Avould 

 probably prove this lobus to be a modified portion of the 

 acusticum system. 



According to Haller no fibres from the inner sensory 

 oblongatagebeit (Lobi vagales) enter either of the trigeminal 

 roots of Scyllium, that fish thus agreeing with Acipenser in 

 the total or practical absence of communis fibres, as such, in 

 the so-called trigeminal roots. 



The two roots of Trigeminus II of Scyllium thus seem to 

 be the exact homologues, in so far as the central regions from 

 which they take their origins are concerned, of the two roots 

 of the same nerve in Acipenser, and it may be assumed that 

 the several peripheral branches that arise from the two roots 

 in the two fishes have a similar distribution, though this 

 cannot be definitely confirmed from Haller's descriptions. A 

 bundle of fibres from each of the two roots of Scyllium is 

 said by Haller to be sent to the so-called second trigeminus 

 ganglion, from which the ramus ophthalmicus superficialis, 

 and that nerve alone, has its origin. The remaining fibres of 

 the two roots are said to enter the Gasserian ganglion. From 

 the hind edge of the latter ganglion, and even partly as a 

 part of the dorsal root of Trigeminus II, four branches, said 

 to be lateral branches of the Trigeminus, are said to always 

 arise. The three .distal ones of these four branches always 

 unite to form the ramus oticus, this last nerve being thus 

 formed of three separate branches, as it is in Mustelus. The 



