322 



ZOOLOGY 



SECT. 



TV 



FIG. 064. Carpus of Lacerta 

 agilis, (left) from above. R. 

 radius ; U. ulna ; c. centrale ; 

 i. interme iium ; r. radiale ; u. 

 ulnare: 15, the five distal 

 carpals : t, pisiform ; / V, the 

 five metacarpals. (From Wieder- 

 shehn's Comparative Anatomy.) 



convex articular surface for the carpus. The carpus (Fig. 964) is 



composed of ten small polyhedral or rounded carpal bones. These 



consist of a proximal row containing 

 three, viz., the radiale (?*), ulnare (u\ 

 and intermedium (i), of a centrale (c), 

 and of a distal row of five (1-5) ; with an 

 accessory or pisiform (f) bone attached 

 to the distal epiphysis of the ulna on its 

 post-axial side. The first digit or pollex 

 consists of a metacarpal and two phal- 

 anges, the second of a metacarpal and 

 three phalanges, the third of a meta- 

 carpal and four phalanges, the fourth of 

 a metacarpal and five phalanges, and the 

 fifth of a metacarpal and three phalanges. 

 The number of phalanges in the first 

 four digits is, therefore, one more than 

 the serial number of the digit. 



The pelvic arch (Fig. 965) consists of 

 two triradiate bones, the ossa innominiata, 



each ray being a separate bone. On the outer side at the point 



from which the rays diverge is a concave articular surface the 



acetctbulum (Ac) for the head of the femur. From the region 



of the ace tabu him 



one of the rays, 



the ilium (/), a 



compressed rod, 



passes upwards and 



backwards to arti- 

 culate with the 



sacral region of the 



spinal column. A 



second ray the 



pubis (P) passes 



downwards and 



forwards to meet 



its fellow in the 



middle lino, the 



articulation being 



termed the pubic 



sympJiysis. In the 



middle line in 



front, between the 



anterior ends of the 



pubes, is a small nodule of calcified cartilage, the epipubis (Ccp\ 



The third ray or ischimu (Is) runs downwards and backwards, and 



articulates with its fellow in the ischiatic symphysis, the ventral 



FIG. 965. Pelvis of Lacerta vivipara, from the ventral side. 

 Ac. acetabulum ; Ctp. epi-pubis. Fo'. foramen for obturator 

 nerve (obtutator foramen); Hp. h. hypo-ischium ; /. ilium; 

 1 1, process representing the pre-acetabular pai-t of the ilium ; 

 Is. ischium ; P. pubis ; PP. pre-pubis. (From Wie'dersheim's 

 Comparative Anatomy.) 



