1 74 STRONG. [Vol. X. 



cephalad, more ventral, and issuing from the medulla by two 

 roots, and (2) V yS further caudad and dorsad, and issuing from 

 the lobus trigemini by two rootlets, one dorsal to the other. 

 V/3 proceeds above Va and is closely united also to the 

 Facialis root V 7 VII, part of whose fibres issue just above the 

 VIII. 



Gegenbaur's anterior root, Y a, is the Trigeminus proper, 

 including both the sensory element from the ascending tract 

 and the motor root. His most dorsal root of V b, i.e., V a, is 

 the one derived from the lobus trigemini. V /3 is, probably, the 

 lateral line root from the tuberculum acusticum. His Facialis 

 is the motor root plus, possibly, a root from the lobus vagi 

 (vide infra, p. 193). 



In Jackson and Clarke's account, Va=: Gegenbaur's N a and 

 Vy3= Gegenbaur's Va. V7 VII is probably compound. 

 That portion of its fibres issuing above the VIII may be 

 derived from the tuberculum acusticum, — in fact must be 

 unless Jackson and Clarke are mistaken in deriving both 

 rootlets of V /3 from the lobus trigemini — and may be also, in 

 part, derived from the lobus vagi (compare Goronowitsch and 

 see below, p. 193). This root must also, of course, contain 

 motor fibres. 



Marshall and Spencer (43) describe, in Scylliimi, a R. oph- 

 thalmicus superficialis from the VII having a course closely 

 parallel and superficial to the corresponding trigeminal branch, 

 a buccal branch whose proximal portion forms a connecting 

 branch with the V, and whose distal portion proceeds parallel 

 and superficial to the maxillary branch of the V, and a posterior 

 or hyoidean branch. With respect to the first two, the princi- 

 pal difference between it here and in Amphibia seems to be 

 that the forking into the two branches, Rr. ophthalmicus 

 superficialis and buccalis, takes place more distally in the 

 latter, so that the common trunk of the two forms the connect- 

 ing branch and contains the ganglion. Respecting the hyoidean 

 branch, they do not seem to be aware that the cutaneous R. 

 mandibularis externus is, in part, a nerve to mucous canals 

 similar to the two preceding branches. They also fall into the 

 error, the existence of which seems to have been first pointed 



