184: 



ZOOLOGY. 



cartilaginous support. These claspers form the readiest 



means of de- 

 termining the 

 sex of a speci- 

 men before 

 dissection. 



14. Ner- 

 vous System. 

 The spinal 

 -T-HALAMCMC: cord is very 

 like that of 



_~. - of>r/c toee previous types. 

 ra?F The spinal 



cAai.LUAf nerves are as 

 numerous as 

 the vertebrae. 

 Their dorsal 

 and ventral 

 roots arise 

 alternately ', not 

 in the same 

 vertical plane 

 as in previous 

 types. They 

 pass through 

 the vertebral 

 column by 

 separate open- 

 ings (fig. 93), 

 and only unite 

 outside it. 



Fig. 97. BRAIN, CRANIAL NERVES AND AUDITORY ORGAN 

 OF DOGFISH. 



Dorsal view ; cut edge of skull in black. (Partly after Wieder- 

 sheim.) The separate small figure is a side view of the 

 internal ear. 



but the . cavities are all very large, and 

 lobes and cerebellum, as well as the optic 



15. The 

 Brain shows 

 the same 

 essential parts 

 as in the frog, 

 the olfactory 

 lobes, contain 



