12 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



canal. The pectoral girdle, which supports the fore limbs 

 and protects the organs in the anterior part of the body, is 

 composed of several bony or cartilaginous pieces. The large 

 flat suprascapula lies above the vertebral column; the scapula, 

 clavicle and coracoid pass downward on either side and connect 

 with the sternal bones in the median line. The large humerus 

 of the arm is attached to the pectoral girdle between the scapula 

 and coracoid. The forearm consists of the fused radius and 

 ulna, the radio-ulna. The wrist contains six small carpal 

 bones. In the hand are the five basal metacarpal bones, and 

 beyond them the phalanges, two each in the second and third 

 digits and three in the fourth and fifth digits. The pelvic 

 girdle is shaped somewhat like the "wish-bone" in fowls, the 

 long bone, the ilium, on each side connecting with the trans- 

 verse process of the ninth vertebra. The bones of the hind 

 limb consist of the femur, tibia-fibula, four small tarsal bones, 

 the astragalus and cakaneum, the digital bones, consisting of 

 the metatarsals and the phalanges, and the small calcar, or 

 prehallux. 



The Nervous System. -The nervous system can best be 

 dissected out in specimens that have been macerated in 20 per 

 cent, nitric acid for some time. The brain consists of the two 

 large fused olfactory lobes, the elongated cerebral hemispheres, 

 the rounded optic lobes, the small cerebellum and the long 

 medulla oblongata which gradually narrows into the spinal cord. 

 The optic chiasma, the infundibulum and the hypophysis are 

 on the ventral side. The spinal cord extends through the 

 neural canal in all the vertebrae and ends in the urostyle. The 

 brain and spinal cord give off many large nerves which branch 

 and subdivide and finally reach all the tissues of the body. The 

 s\m pathetic system consists of two principal nerve trunks, one 

 on each side of the vertebral column, and a series of nerves 

 which are distributed to the internal organs. 



Life History and Habits. In the spring the frog lays her 

 eggs in masses in the water of ponds or ditches. The gelat- 

 inous substance which surrounds them soon swells so that the 

 egg-mass looks like a ball made up of little round bits of jelly 

 with black centers. The toad's eggs are similar to the frog's 



