THE STinV or A.\ AMMAL TYI'E 7 



The l)()(ly (■(•inpriscs two regions, htail and Innih. Tlio arms 

 and legs are regarded as appendage.s of the latter. Note the 

 color pattern, the distribution and intensity f>f color, and any 

 striking markings upon the i)ody. 



When the frog once confronts its food it is still in need of pro- 

 visions for getting the food into its digestive organs. Reflect 

 upon the usefulness of hands and jaws in this service, bearing 

 in mind the non-grasping nature of the hands. 



In the forelimb or arm, beginning at the body, identify upper 

 arm or brachium; the shoulder joint and its freedom of movement ; 

 forearm or antebrachium; elbow joint and its movements; wrist; 

 hand or manus with digits (fingers). Why is your own hand 

 efficient as a prehensile (grasping) organ? What is lacking in the 

 frog's hand? What is suggested by the structure, form, attitude, 

 and flexibility of the arm in its service to the frog? 



In the hind limb identify thigh, shank, ankle, foot or pes with 

 digits (toes). Locate and compare the hip, knee, and ankle 

 joints with the corresponding joints of the arm. How many 

 digits in the foot? Are the digits of the hand and foot similar 

 in arrangement and in length according to numerical position? 

 Compare the palm of the hand and sole of the foot; the heel 

 with the corresponding part of the hand. Do these peculiarities 

 of hands and feet suggest any sort of advantages to the animal? 



If not already familiar with both the terrestrial and aquatic 

 modes of locomotion of the frog make such observations upon 

 living specimens. Attempt a correlation of these observations 

 with the position of the limbs when at rest, the movements and 

 service of parts in active locomotion, determining, if possible, 

 a general locomotor function which may be assigned to each 

 pair of limbs, taking into consideration the need of buffers, 

 propellers, steering devices, leverage, rigidity, and flexibility. 

 If the limbs meet such needs, explain how it is done. 



Organs of Special Sense. — The awareness of the frog to sur- 

 rounding conditions can l^e readily determined by observation 

 and simple experiments performed upon the living animal. 

 The means of gathering information from the surroundings are 

 sense organs (receptors) either located within restricted areas 

 as the organs of vision, smell, taste, and hearing or scattered as 

 the organs of touch and other senses. Some of these organs 

 cannot be observed by macroscopic study. Touch corpuscles 

 and fine nerve endings in the skin render the frog sensitive to 



