THE GARDEN TOAD 21 



below this gullet an elevation in which is a perpendicular 

 slit, the glottis. This is the upper end of the laryngotracheal 

 chamber, and the flaps within on either side of the slit are 

 the vocal cords. 



Note at the posterior end of the body in the median line 

 an opening. This is the anal opening or anus. Note the 

 general make-up of the toad. How do its arms compare 

 with our own? How do its fore feet (hands) differ from its 

 hind feet? Note that the body is covered by a tough envel- 

 oping membrane, the skin. In the skin are many glands 

 which by their excretion keep it soft and moist. 



Internal Structure. TECHNICAL NOTE. With a fine pair of 

 scissors make a longitudinal median cut through the skin of the venter 

 from the anal opening to the angle of the lower jaw. Spread the cut 

 edges apart and pin back in the dissecting-pan. 



Note the complex system of muscles which govern the 

 movements of the tongue. Observe a number of pairs of 

 muscles overlying the bones which support the arms. These 

 are attached to the pectoral or shoulder-girdle. Note the 

 large sheet of muscles covering the ventral aspect of the 

 toad. These are the abdominal muscles, which consist of 

 two sets, an outer and an inner layer. Note that posteriorly 

 the abdominal muscles are attached to a bone. This is the 

 pubic bone of the pelvic girdle which supports the hind legs. 



TECHNICAL NOTE. With the scissors cut through the muscles of 

 the body-wall at the pubic bone and pass the points forward to the 

 shoulder-girdle. Separate the bones of the shoulder-girdle and pin 

 out the flaps of skin and muscle to right and left in the dissecting-pan 

 (see fig. 8). Cover the dissection with clear water or weak alcohol. 



Note two large conspicuous soft brown lobes of tissue. 

 These form the liver, an organ which produces a secretion 

 that assists in the process of digestion. Note just anterior 

 to the liver and extending between its two lobes a pear- 

 shaped organ, the heart. The lower end or apex of the 



