12 ELEMENTARY ZOOLOGY 



TECHNICAL NOTE. The teacher should be provided with several 

 well-cleaned skeletons of the toad in order that the bones may be 

 carefully studied. Boil in a soap solution a toad trom which most 

 of the muscles and skin have been removed (see p. 452). Leave in 

 this solution until the muscles are quite soft and then pick off all 

 bits of muscles and tissue from the bones. If this is carefully done, 

 the ligaments which bind the bones will be left intact and the 

 skeleton will hold together. 



Note that the skeleton (fig. 2) consists of a head portion 

 which is composed of many bones joined together to form 

 a bony box, the skull; of a series of small segments, the 

 vertebrce, forming the vertebral column, which with the 

 skull forms the axial skeleton; and of the appcndicidar 

 skeleton, consisting of the bones of the fore and hind limbs. 

 Note that the skull is composed of many bones joined 

 together, some by sutures, while others are fused. Do 

 the limbs attach directly to the axial skeleton ? The 

 anterior limbs (arms) articulate with the pectoral or 

 shoulder-girdle. The arms will be seen to be made up 

 of a number of bones placed end to end. Note that the 

 uppermost, the Jiumerus, is attached to the pectoral 

 girdle, while at its lower end it articulates with the 

 radio-ulna. At the lower end of the radio-ulna is a small 

 series of carpal bones which afford attachments for the 

 slender finger-bones, \\\e plialanges or digit a I bones. The 

 bones of the leg are articulated with a closely fused set 

 of bones, the pelvic girdle. The leg-bones, proceeding 

 from the pelvic girdle, are named femur, tibio-filnda, 

 tar sal bones, and phalanges or digits. To what bones of 

 the arm do these correspond ? Determine the other 

 principal bones of the skeleton by reference to figure 2. 



TECHNICAL NOTE. In a specimen which has been macerated 

 for some time in 20% nitric acid dissect out the nervous system. 

 Place the specimen in a pan ventral side uppermost and pin out. 

 Carefully pick away the vertebrae and the roof of the mouth-cavity, 

 thereby exposing the central nervous system, which will appear 

 light yellow. 



