5 88 



AMPHIBIA. 



Muscular system. The muscles are enswathed in con- 

 nective tissue. They consist of bundles of striated fibres, 

 and at their ends or at one of them they are usually con- 

 tinued into tendons, 

 which are more or 

 less directly attached 

 to parts of the skele- 

 ton. 



For an account of 

 the musculature of 

 Vertebrate types, 

 the student is re- 

 ferred to the 

 guides to practical 

 work cited in the 

 Appendix. 



Nervous system. 

 The brain, covered 

 with a darkly pig- 

 mented pia mater, 

 has the usual five 

 parts. 



The elongated 

 cerebral hemi- 

 spheres have 

 "olfactory lobes" 

 in front of them, 

 and are con- 

 nected by an- 

 terior and 



FIG. 319. Nervous system of frog. After 

 Ecker. 



i-io, The cranial nerves ; oc., eyes ; crb.^ in front oi 

 optic chiasma ; to., optic tract ; sym., sympa- 

 thetic system ; tnsfi., spinal cord ; sp., spinal 



posterior com- 

 missures, and 

 by a hint of a 

 "corpus cal- 

 losum " (?). 



The thalamencephalon gives origin dorsally to a pineal 

 outgrowth. The pineal body lies outside the skull in 

 the tadpole, but is partially atrophied in the adult, so 

 that little more than the stalk is left. On the ventral 

 side will be seen the chiasma or interlaced crossing of 

 the optic nerves, and a tongue-shaped mass (the tuber 



