NERVOUS SYSTEM OF FROG 



659 



expanded transverse processes of the ninth or sacral 



vertebra. Each limb of the V is an ilium ; the united 



posterior part consists of a fused pair of ischia, and a ventral 



cartilaginous pubic 



portion. Ilium, 



ischium, and pubis 



unite in bounding 



the deep socket or 



acetabulum with 



which the femur 



articulates. 



The skeleton of 

 the hind-limb con- 

 sists of a thigh bone 

 or femur, a lower 

 leg formed from 

 the united tibia and 

 fibula, an ankle 

 region or tarsus 

 including two long 

 proximal elements 

 — the astragalus or 

 tibiale and the cal- 

 caneum or fibulare 

 — -and three imper- 

 fectly ossified distal 

 elements, five meta- 

 tarsal bones, and 

 five toes. The first 

 toe or hallux has 

 two phalanges, the 

 second also two, 

 the third three, the 

 fourth four, the 

 fifth three, and, 

 finally, outside the 

 hallux there is a 



" calcar," which looks like an extra toe, and consists of 

 three pieces. The astragalus is in line with the first toe. 

 The long bones of the skeleton show readily separable 

 calcified terminal caps. 



Fig. 380. — Nervous system of frog. — After 

 Ecker. 



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

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

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

 nerves. 



