NECTURUS 21 



as follows: a proximal row of two, a radiale on the radial side, and 

 an ulnare on the other, to which is usually fused a middle element, 

 the intermedium. The distal row consists of three carpales, 

 while a centrale lies between the two rows. 



The carpus is followed by the palm, metacarpus, and this 

 in turn by the digits. How many metacarpal bones, and how 

 many bones (phalanges) in each finger? (The thumb pollex 

 or first digit is absent.) 



The pelvic girdle is largely cartilaginous, its two halves 

 being fused in the mid-ventral line. On either side the pelvis 

 bears a bony element, the ilium, which articulates by the inter- 

 vention of a cartilage with the sacrum. At the base of the 

 ilium is a pit, the acetabulum, for the articulation of the 

 hind limb. The ventral half of the girdle forms a flat plate, the 

 anterior part of which is the pubis, the posterior the ischium. 

 In the ischial region is an ossification, and the limits between 

 ischium and pubis are indicated by a small obturator foramen 



The bones of the hind limb correspond very closely with those 

 of the arm femur to humerus, tibia and fibula to ulna and 

 radius, tarsus to carpus (tibiale, fibulare, centrale, tarsales), 

 metatarsals to metacarpals except that there are two ridges 

 (cresta ventralis, c. lateralis) on the femur. As in the hand the 

 first digit (hallux) is lacking. 



Draw both girdles and the skeleton of each limb, indicating 

 in your drawing bone and cartilage. 



