e have transverse
processes, but no ribs.

Section 14. The fore-limb (Figure 6, Sheet 12) consists of an upper
segment of one bone, the humerus, as in the rabbit; a middle section,
the radius and ulna, fused here into one bone, and not, as in the
mammalian type, separable; of a carpus, and of five digits, of which
the fourth is the longest. The shoulder girdle is more important and
complete than that of the higher type. There is a scapula (sc.) with an
unossified cartilaginous supra-scapula (s.sc.); the anterior border of
the scapula answers to the acromion. On the ventral side a
cartilaginous rod, embraced by the clavicle (cl.) (a membrane bone in
this type), runs to the sternum, and answers to the clavicle of the
rabbit. In the place of the rabbit's coracoid process, is a coracoid
bone (co.), which reaches from the glenoid cavity to the sternum; it is
hidden on the right side of Figure 6, which is a dorsal view of the
shoulder girdle. There is a pre-omosternum (o.st.) and a
post-omosternum, sometimes termed a xiphisternum (x.).

Section 15. Figure 7 shows the pelvic girdle and limb of the frog.
There is a femur (f.); tibia and fibula (t. and f.) are completely fused;
the proximal bones of the tarsus, the astragalus (as.), and calcaneum
(cal.) are elongated, there are five long digits, and in the calcar (c.) an
indication of a sixth. With considerable modifications of form, the
three leading constituents of the rabbit's pelvic girdle occur in
relatively identical positions. The greatly elongated ilium (il.)
articulates with the single (compare Rabbit) sacral vertebra (s.v. in
Figure 5). The ischium (is.) is relatively smaller than in the rabbit, and
the pubis (pu.) is a ventral wedge of unossified cartilage. The shape of
the pelvic girdle of the frog is a wide departure from that found among
related forms. In connection with the leaping habit, the ilia are greatly
elongated, and the pubes and ischia much reduced. Generally
throughout the air-frequenting vertebrata, we find the same
arrangement of these three bones, usually in the form of an inverted.
Y-- the ilium above, the ischium and pubis below, and the acetabulum
at the junction of the three.

Section 16. The uro-genital organs of the frog, and especially those
of the male, correspond with embryonic stages of the rabbit. In this
sex the testes (T., Sheet 13) lie in the body cavity, and are white
bodies usually dappled with black pigment. Vasa efferentia (