SECTION VII. THE SKELETON 



// a prepared skeleton is not available, skin a jrog and re- 

 move the viscera and as much of the musculature as possi- 

 ble. Boil for five minutes (repeated if necessary) in soap 

 solution (see Appendix) , and pick away the remainder of 

 the soft parts. 



The skeleton of the frog is entirely an endoskeleton. It is 

 composed of the axial skeleton, including the skull, verte- 

 brae and sternum; and the appendicular skeleton, consisting 

 of the pectoral and pelvic girdles and the bones of the 

 limbs. 



The skull consists of certain derm-bones which form the 

 dermocranium (D), axial elements which form the neuro- 

 cranium (N), and derivatives of the gill arches (visceral 

 skeleton) which form the splanchnocranium (S). 

 In the skull identify the following bones from the dorsal 

 aspect, commencing at the cephalic end. 



208. The premaxillaries (D) are the most anterior bones 

 bearing teeth. 



209. The maxillaries (D) also bear teeth and form the 

 greater part of the upper jaw. 



210. Articulating with the premaxillaries at their caudal 

 ends are the nasals (D), which send long processes 

 laterad to join the maxillaries. 



211. Caudal to the nasals, and partially overlaid by them, 

 is the sphenethmoid (N). 



212. This is overlaid caudad by the long f ronto-parietals 



(D). 



35 



