244 Joi'RNAL OF COMI'AKATIAE NHUHOI.OCiV. 



caudal one dividing peripherally. The ninth nerve is much 

 smaller than either branch of the vagus, and arises from the 

 caudo-ventral aspect of the very tumid trigeminal lobe, a 

 short distance caudad of the eighth. It soon receives a small 

 anastamosing branch from the cephalic root 6f the vagus, 

 which returns to the latter a little farther peripherad, but 

 proximad of the ganglion. The distribution of the ninth is 

 as described in the cat fish. 



The eighth has two distinct roots, but the cephalic branch 

 is closely associated with the seventh, which is distinct 

 from the fifth beyond Gasser's ganglion, and is distributed to 

 the opercular and gular regions. 



At its roots the fifth nerve is composed of three chief divi- 

 sions, but beyond the ganglion there are five, the most dorsal 

 of which is the trigeminal accessory nerve of the lateral line. 



The sixth is small, and no separate root was found. The 

 third and fourth are small, but normal, and the remaining 

 nerves oflier no peculiarities. 



PLATE XIX. 



Fig. 1. Dorsal view of the brain of the buftalo-fish, Carpiodes 

 tumidus,^. and G. Z,.t' »-., vagal lobes; VIII, eighth nerve; Afa. I., 

 mesaxial lobe of the cerebrum; C/ni. /., cuneate lobe; L. /., lateral lobe; 

 6)/., optic ner^e. 



Fio-. 2. Lateral view of the same brain. Hyp., hypophysis; 

 F. oc, occipital fissure; F. Sy/., Sylvian fissvire; J' 1 d., dorsal root of 

 cephalic division of trigeminus; T' /. t., ventral division of the same; 

 I^ ..^., caudal trigeminus. 



Ft OS. .J-o. Three views of the brain of the black-horse, C yclept us 

 elongafits. II v p., hypophysis; 7'. r/;/., tuber cinereum; -\o\ /., vagal 

 lobe; Jfpd., hypoaria. 



Fios. <',-',. Lateral and dorsal views of the brain of the gizzard- 

 shad, Dorosoma crcpidinniim . 



Fig. S. Dorsal view of the brain of the moon-eye, Hyodoii fergi- 

 stis. The hemispheres are divaricated and deprived of the pallium. 



Figs. !)-l I. Three views of the brain of the common eel. 



PLATE XX. 



A series of transections of the brain of the black-horse, Cycleptns 

 elongatus. A description of histological details will be given in a sub- 

 sequent paper. 



