42 THE FROG 
the distal end of the humerus, and bears a projection known as 
the olecranon process. 
The wrist or carpus contains six small carpal bones arranged 
in two rows. In the proximal row there are three bones: one 
corresponding to the radius, the radiale; one corresponding to the 
ulna, the ulnare; and one between the two, the centrale. In 
the distal row we find, beginning on the radial or thumb side, two 
small bones corresponding respectively to the rudimentary thumb 
and the second digit; these we call distals 1 and 2. There is a 
much larger crescentic bone which represents distals 3, 4 and 5 
fused together. 
The hand or manus exclusive of the wrist has four complete 
digits, and a rudimentary thumb. Adjoining the carpal bones are 
five metacarpals; the small first metacarpal on the preaxial side 
represents the thumb (pollex). The second and third meta- 
carpals are followed by two phalanges each, the fourth and fifth 
by three each. The phalanges form the fingers. 
Draw (X 4) the manus, including the wrist. 
3. The pelvic girdle or pelvis as a whole is V-shaped. In the 
adult frog the girdle is placed very obliquely, so as to be nearly 
parallel to the vertebral column instead of at right angles to it. 
The two limbs of the V diverge anteriorly and are fastened to the 
strong backwardly directed transverse processes of the ninth or 
sacral vertebra. Each lateral half of the pelvic girdle is com- 
posed of three parts, which meet in the acetabulum, a rounded 
cavity which receives the head of the femur and forms with it the 
hip-joint. The three parts are: 
The ilium, the long bone forming a limb of the V. Observe 
on its dorsal surface a prominent ridge, the iliac crest. The 
ilium is attached in front to the tip of the transverse process of 
the ninth vertebrae; posteriorly it forms the anterior and dorsal 
half of the acetabulum. Posteriorly the two ilia meet and are 
united in the median plane to form the iliac symphysis. 
The ischium forms the postero-dorsal portion of the pelvis 
and the posterior third of the acetabulum. The ischium is 
roughly oval in form, with a dorsal prominence. The two ischia 
are united by the whole of their median surfaces, forming the 
ischial symphysis. 
