336 



ZOOLOGY 



and are carried through them to the cloaca, receiving on 

 their journey tlie jelly, which swells up enormously when the 

 eggs enter the -water at the time they are laid and while the 

 sperm is making its way to the eggs. 



ol h<he 



.ffXJ7- 



cerebrum 



Zn Trap I 

 Jnf 



optic lobe 



ccrebeUum 



ol. lobe 



cerebrum 



optic lobe 



2M 



Fig. 310. — The l_ir;iin of the froK viewed from ;ibo-\-e (A) and l:)elow (B). 

 /, olfaetory nerve Koiiif;to olfactor\' lolie {ol. lobe). II, optic nerve going to 

 Tr.opl. the optic tract of the brain. Ill, IV, VI, IX, X, XI, XII (1), 

 other ner\'es to biain. Z.H, mid brain : .In.f, infundibuhim. Aled, the 

 medulla with it^^ fir.st ner\'e at 1. From Wiedersheim, " Comp. Anat." 



The muscular system of the frog is reduced on account of its 

 shortened body. In the tailed amphi1iians the ringed condi- 

 tion of the body musculature is still evident (Fig. 315), but 

 in the frog this ajipears only in the straight abdominal muscles. 



