520 



AMPHIBIA 



[CH. 



The Amphibian limb, on the other hand, is what is known as a 

 pentadactyle limb ; that is to say, it is constructed on the familiar 

 type of the human limb, and the median fin when present has no 

 fin-rays (Figs. 251 and 253). 



The pentadactyle or five-fingered limb (Gr. TreWe, five ; 

 a finger), also called the cheiropterygium (Gr. \tip, a hand; 

 yiovj little wing, hence an appendage), consists of three segments, a 

 proximal, containing one long bone ; a middle, containing two bones 

 placed side by side and occasionally fused into one ; and a distal, 

 containing a series of small squarish cartilages or bones arranged in 

 lines so as to give rise to a series' of diverging rays; the last- 

 mentioned constitute the skeleton of the fingers and toes. In the 

 proximal part of this lowest segment the bones are much crowded 

 together and the rays tend to coalesce: this part has received a 

 special name, as has also the portion where the rays although 

 separate are embedded in the same muscular mass. 



The fore-limb is called 

 the arm, and its divisions 

 the brachium or upper 

 arm, the antebrachium 

 or fore-arm, and the 

 man us or hand (B, Fig. 

 251). The hind-limb is 

 the leg, and its divisions 

 are the femur or thigh, 

 the crus or shank, and the 

 pes or foot (A, Fig. 251). 

 The manus is divided 

 into three regions, viz. : 

 (a) the carpus or wrist 

 where the rays tend to 

 coalesce; (6) the meta- 

 carpus or palm where the 

 rays although separate are 

 bound together by flesh 

 and skin- (c) the digits 

 or free ends of the rays. 

 The pes is similarly divided into tarsus or ankle, metatarsus 

 or sole, and digits or toes. 



The bone of the brachium is called the humerus, that of the 

 femur bears the same name as the segment to which it belongs ; 



FIG. 251. A. Skeleton of a right posterior, 

 B. skeleton of a right anterior limb of a 

 Newt, Molge cristata x 1. 



1. Femur. 2. Tibia. 3. Fibula. 



4. Tibiale. 5. Intermedium. 6. Fibu- 

 lare. 7. Centrale of tarsus. 8. Tarsale 1. 

 9. Tarsalia 4 and 5 fused, i, n, HI, iv, 

 V. Digits. 10. Humerus. 11. Eadius. 

 12. Ulna. 13. Badiale. 14. Intermedium 

 and ulnare fused. 15. Centrale of carpus, 

 the pointing line passes across carpale 2. 

 16. Carpale 3. 17. Carpale 5. 



