Hkkkick, yiorpliology of Brain oj Bony Bisl/cs. 227 



ventricles by a wide foramen of Monro. Aula and portae can 

 scarcely be separately distinguished. The median fissure is 

 so poorly developed that the lateral ventricles of the two 

 hemispheres are practically continuous for the whole length 

 of the cerebrum. The limits of the cerebral ventricles are 

 implied in the description of the pallium given above. They 

 pass from the median fissure laterad to the sinus rhinalis of 

 each side and envelop the entire cephalic aspect of the basal 

 lobes. The basal lobes are entirely separated, except in the 

 region of the anterior commissure, by the cerebral ventricle, 

 down, even to the extreme ventral limit of the cerebrum, 

 where the ventricle is bounded by a membranous floor. The 

 relations of the cerebral ventricles to the ventricles of the 

 olfactory lobes are discussed in the section devoted to the 

 rhinencephalon. 



DESCRIPTION OF PLATE XVII. 



Fig. I. Dorsal view of the brain of the adult mud cat fish, or 

 yellow cat, Pilodicfis olix'aris Gill and Jordon. The olfactory lobes, 

 with most of the crura, have been removed. The trigeminal, vagus and 

 first spinal nerve-roots are shown. X 2. 



Fiir. 2. Dorsal view of the brain of a young bull-pout, Aiiiiiirus 

 catiis Gill, three inches long. The olfactory lobes have been removed. 

 X 4- 



Fig. .1. Dorsal view of the brain of a much younger bull-pout, one 

 inch long. The olfactory crura are reduced until the olfactorj lobes are 

 closely appressed to the hemispheres. X 10. 



Fig. 4. Ventral view of the brain of the adult mud cat, Pilodicfis 

 olivaris. The olfactory lobes, hypophysis and saccus vasculosus have 

 been removed. The Roman numerals refer to cranial nerves. X 2. 



Fig. 5. Lateral view of the brain of Pilodicfis olivaris. designed 

 to illustrate the distribution of the cranial nerves. The various nerve- 

 roots are retained, as nearly as may be, in their natural positions. The 

 olfactory lobes have been removed; 0/., olfactory crus; ;/. op., optic 

 nerve; Vj, Vg, V3, V^, V5, Vg, V-, the seven principal branches of the 

 trigeminus nerve; F^, Fg, F3, F^, the four principal foramina of the 

 trigeminus verve; F//, the facial nerve; //. dep. op., nerve of the 

 depressor operculi; ii. lev. op., nerve of the levator operculi; VIII, 

 acoustic nerve; /A', glosso-pharyngeal nerve; g^, ganglion of the 

 vagus nerve; ii.lL, nerve of the lateral line; A' vise, visceral branch of 

 the vagus; A' ///., thoracic branch of the vagus; n. d. /., nerve of the 

 depressor of the pectoral fin; n. I. p., nerve of the levator of the pectoral 



