538 



STRUCTURE OF VERTEBRATA 



several elements, a " hand " with metacarpal bones in the 

 *' palm," and with fingers composed of several phalanges. 

 The hind limb — from Amphibians onwards — consists 

 of a femur articulating with the girdle, a lower leg com- 

 posed of a tibia and fibula lying side by side, an " ankle " 



-^ 



Fig. 304. — Ideal fore and hind limb.— After Gegenbaur. 



H., Humei-us ; R., radius ; U ., ulna ; /■'., ladiale ; u' ., ulnare ; i., intor- 

 medium ; c, centrale ; 1-5, carpalia bearing the corresponding meta- 

 carpals (mc.) and digits with phahmges [ph.). 



/., Femur ; ti., tibia ; fi., fibula ; /., intermedium ; t., tibiale (astragalus) ; 

 /., fibulare (os calcis) ; c, centrale ; 1-5, tarsalia bearing the corre- 

 sponding metatarsals {mt.) and digits with phalanges (ph.). 



region or tarsus of several elements, a foot with metatarsal 

 bones in the " sole," and with toes composed of several 

 phalanges. 



In Fishes the limbs are fins, i.e. without digits. 



Distinct from the other bones are a few little sesamoids 

 of occasional occurrence, e.g. the knee-pan or patella. 

 They develop in connection with the tendons of muscles. 



