THE GREEN FROG 333 



The bones of the arms are attached to a shoulder-girdle 

 consisting of the shoulder-blades or scapulas (Fig. 166, 4), two 

 coracoids, and two collar-bones or clavicles. A broad breast- 

 bone (sternum) extends a short distance along the median 

 ventral line. Each of the anterior limbs contains one bone in 

 the upper arm, called the humerus (Fig. 166, 5); one bone 

 in the forearm, composed of two bones united, the radius 

 and ulna (Fig. 166, 6) ; six bones in the wrist-region, or car- 

 pus (Fig. 166, 7); four complete sets of bones in the palm 

 (metacarpals, Fig. 166, 8) ; and four complete sets of finger- 

 bones (phalanges, Fig. 166, 9). The metacarpals arid phalanges 

 of the inner digit are rudimentary. 



The leg-bones are attached to the vertebral column by 

 means of a hip 01 pelvic girdle (Fig. 166, 10), of peculiar shape. 

 The skeleton of each leg consists of one bone in the upper, leg, 

 the femur (Fig. 166, 11); one bone in the lower leg, formed 

 from two bones united, the tibia and fibula (Fig. 166, 12) ; five 

 bones in the ankle-region, or tarsus (Fig. 166, 13) ; and five 

 complete sets of phalanges (Fig. 166, 15). A sixth rudimen- 

 tary digit is also present (Fig. 166, 16), consisting of one 

 metacarpal bone and two phalanges. 



The Nervous and Muscular Systems. The nervous system 

 is similar in general plan to that of the perch. The brain has 

 large cerebral hemispheres (cerebrum, Fig. 165, 43), each of 

 which is prolonged anteriorly into an olfactory lobe (Fig. 

 165, 42). The optic lobes (Fig. 165, 44) are also large, but the 

 cerebellum (Fig. 165, 45) is small. Behind the cerebellum is 

 the medulla oUongata (Fig. 165, 40), at the posterior end of 

 which the spinal cord (Fig. 165, 47) arises. The nerves are not 

 shown in the dissection. The muscles are arranged in bands 

 or spindle-shaped masses instead of in segments, and the frog 

 is capable of much more complex movements than the perch. 



The Reproductive System. The spermaries of the male 

 frog (Fig. 165, 49) are bean-shaped bodies lying beneath the 



