A STUDY OF THE SKELETON 



189 



In spite of these great differences in form and function, we 

 find in each appendage bones that correspond to some or all 

 of those in the human arm and leg (compare Fig. 83). 



Frogs have a breastbone, but no well-defined ribs ; snakes 

 have ribs the whole length of the body (sometimes several 



FIG. 83. Skeleton of the Frog. 

 Carp = carpal bones (6) . 



II, Pit = pelvic girdle. 

 R, U = radio-ulna. 



Cor, Cl, Sc = pectoral girdle. 

 Fe = femur. 



Tarsi, Tibl, Fiblr = tarsal bones (5). 

 Ti + Fi = tibio-fibula. 

 F 1 = first vertebra. 

 F K = ninth vetebra. 



/' = rudiment of sixth toe. 

 I, II, III, IV, V = metacarpals and metatarsals. 



hundred pairs), but have no breastbone. In addition to 

 their inside skeleton, turtles have thick shells which are on 

 the outside like the skeleton of an invertebrate (see p. 245). 

 In birds most of the bones are hollow and filled with air, an 

 arrangement that helps to give to these animals some of 

 their buoyancy in flying. 



