MUSTELUS LJEYIS. 215 



probably due to its being so small that it was overlooked, or 

 missed, in dissection. It is, however, to be noticed that 

 neither he nor Collinge (13) describe, in Acipenser, either a 

 preopercular or mandibular section of the lateral canals. This 

 thus certainly calls for further investigation. 



According to Goronowitsch (p. 481) neither the ophthal- 

 micus superficialis nor the ophthalmicus profundus of his 

 descriptions of Acipenser receives a communicating branch 

 from the facialis roots. If, then, Kingsbury is coi'rect in his 

 assertion that the communis component of the Y — VII com- 

 plex of Acipenser is derived entirely from the dorsal root of 

 the facialis of Goronowitsch, it is evident that the communis 

 fibres, if they exist as such in either of the two ophthalmic 

 nerves of the fish, must be derived from those fibres that are 

 said by Goronowitsch (p. 479) to connect the ganglion of 

 Trigeminus II with the nervus facialis. As the communis 

 elements that could possibly enter into the ophthalmic nerves 

 by this route would necessarily be limited, they certainly 

 cannot represent the nervous supply of the nerve-sacs of the 

 snout of the animal, those organs thus quite certainly being 

 innervated by fibres derived from one of the two roots that 

 Kingsbury and -lolmston both consider as lateral sensory 

 ones ; that is, the nerve-sacs of Acipenser and the ampullas 

 of selachians are quite unquestionably innervated in the same 

 manner, and are hence homologous organs. 



In Amia, both Kingsbury (40) and myself (3), in works 

 published at nearly the same time, find two of the trigemino- 

 facial roots arising close to the root of the nervus acusticus. 

 Kingsbury calls them Vllb and A^IIaa, and says that Vllb 

 enters the tuberculum acusticum, and is composed of coarse 

 fibres identical with those of the lateral line nerve ; while 

 Vllaa arises " from the fasciculus communis system which 

 disappears with the exit of this root " (p. 7). The spinal Yth 

 tract of the fish is said by Kingsbury (p. 23) to probably 

 furnish all the general sensory elements of the trigeminal 

 nerve. The root here called Vllaa by Kingsbury was con- 

 sidered by me (1. c, p. 596) as the antero-dorsal root of the 



VOL. 45, PART 2. — NEW SERIES. Q 



