S 6S 



AMPHIBIA. 



toe. The long bones of the skeleton show readily separable 

 calcified terminal caps. 



Muscular system.- -The muscles are enswathed in con- 

 nective tissue. They 

 consist of bundles of 

 muscle fibres, and at 

 their ends or at one 

 of them they are 

 usuallycontinued into 

 strong tendons, which 

 are more or less 

 directly attached to 

 parts of the skeleton. 

 For an account of 

 the musculature of 

 Vertebrate types, the 

 student is referred to 

 the guides to practi- 

 cal 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 

 posterior com- 

 missures, and by a hint of a " corpus callosum " (?). 

 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 



FIG. 278. Nervous system of frog. After 

 Ecker. j 



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

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

 thetic system; msp., spinal cord; s/>., spinal 

 nerves. 



