306 



ACTINOP TER YG1I 



lower forms, but may be stalked in the Teleostei. The ganglionic 

 cells become clearly stratified (Goronowitsch [180], Mayser [298], 

 Rabl-Riickert [340], Johnston, Mihalkowikz). 



Fio. 282. 



Median longitudinal section of the brain of Acipenser ruthenus. (After Goronowitsch, from 

 Sedgwick's Zoology). Cb, cerebellum ; c7i, optic ehiasma ; ep, pineal tody ; hy, pituitary body ; 

 pi, roof of telencephalon with choroid plexus ; M, roof of mesencephalon ; pi, roof of myelen- 

 cephalon ; s.r, saccus vasculosus ; V. cavity of telencephalon ; z, cavity of thalamencephalon. 



Fio. 283. 



Left-side view of brain of A, Aeipenser ruthenus ; and B, Amia calm. (After Goronowitscli, 

 from Gegenbaur, Vergl. Anat.) ac, auditory nerve ; Ep, epiphysis ; F, facial nerve ; (?;>, glosso- 

 pharyngeal nerve ; h and hy, hypophysis ; Hh, cerebellum ; L.i, lobus inferior ; L.ol, olfactory 

 lobe ; M, mesencephalon ; N, myelencephalon ; o, optic nerve ; pi, choroid plexus ; Tr' and 

 2Y", trigeminal nerve ; s.v, saccus vasculosus ; Vg, vagus nerve. 



The urinogenital organs are discussed elsewhere (p. 365) ; but 

 it may here be mentioned that the cloaca is lost, the anus opening 

 separately in front, and the genital and urinary ducts lead into a 



