40 The Ohio Journal of Science [Vol. XVII, No. 2, 



In the Elasmobranchs the profundus gangUon is separate 

 from the Gasserian and usually has a separate root even in the 

 adult form. From this profundus ganglion arises the ventral 

 ramus opthalmicus profundus which innervates the cutaneous 

 tissues of the rostrum, and carries ciliary nerves and in one case 

 noted (Acanthias) gives rise to the portio opthalmici profundi, 

 which represents the dorsal branch of the primitive profundus 

 nerve. (See Herrick '99, p. 364). 



In the ganoids several different conditions exist. The 

 Gasserian and profundus ganglia are usually separate in the 

 adult, but a true ramus opthalmicus profundus is seldom 

 present. According to Allis "a small, delicate, apparently 

 degenerate nerve from the profundus ganglion" is in Amia the 

 only remnant of the ramus opthalmicus profundus. There 

 is a large portio opthalmicus profundus which fuses with the 

 ramus opthalmicus superficialis V to form the supra-orbital 

 trunk. 



In teleosts the profundus ganglion is not isolated in the 

 adult (Herrick '99) and no ramus opthalmicus profundus is 

 described for an^^ form so far as I know. Herrick homologizes 

 cutaneous fibres which arise from the Gasserian ganglion and 

 are fused with the radix longa from the ciliary ganghon with 

 the ramus opthalmicus profundus of the Elasmobranchs. 

 Allis takes the position that the ramus opthalmicus profundus 

 is probably entirely wanting in Teleosts (p. 539) and that the 

 ramus op sup V, probably contains the portio op. prof. The 

 ramus opthalmicus profundus, whatever its relation to the 

 muscles of eye (Allis '97, p. 536) always lies under the superior 

 branch of the oculomotor and over the inferior branch of that 

 nerve. In teleosts and ganoids a small branch of the trigeminus 

 which is found dorsal to the oculomotor nerve must undergo 

 a special development, i. e., become enlarged, as the rest of the 

 profundus nerve disappears and become the portio opthalmicus 

 profundus, which may be a separate nerve as in Amia, or be 

 fused with the ramus opthalmicus superficiahs V, as in Teleosts, 

 according to Allis ('97, p. 539). 



In the Amphibia the profundus ganglion is partially or 

 entirely separate from the Gasserian in the embryo, but is 

 always fused in the adult. In the adult Anura the trigeminal 

 complex is also fused with the facial complex, but in the Uro- 



