146 AMPHIBIA (the frog) 



(a) Color? 



(b) Length? 



(c) Trace the ureter from each kidney to the cloaca. 



(d) Sketch the kidneys, the ureters, and the openings 



into the cloaca. 

 5. The Endoskeleton. Carefully dissect off all the flesh and 

 viscera and have the bony skeleton entire and uninjured. 



(1) The Skull. 



(a) Shape? 



(b) Size? 



(c) How many bones in the lower jaw? 



(d) How many occipital condyles, one or two? 



(2) The Spinal Column. 



(a) Number of vertebrae? 



(b) What vertebral processes are longest? Why? 



(c) Why has the frog no ribs? How does it breathe 



without either ribs or diaphragm? 



(d) Urostyle, the long bone at the posterior end of the 



spinal column. 



(1) Shape? 



(2) Is it segmented? 



(3) Use? 



(3) Bones of the Anterior Limbs. In man they are 1 hu- 



merus, 1 radius, 1 ulna, 8 carpals, 5 metacarpals, and 

 14 phalanges, or 30 bones in all. Compare the bones 

 of the frog's anterior limb with those of man. 



(a) What ones are lacking, if any? 



(b) How many in the entire limb? 



(c) Any peculiarity of any bone? 



(4) Bones of the Posterior Limbs. 



(a) Name in order the bones in man's leg. 



(b) Name those in the frog's leg. 



(c) How do they agree? 



(d) How do they differ? 



(e) How do the bones of the posterior limb differ from 

 those of the anterior limb in this specimen? Why? 



(5) The Pectoral or Shoulder Girdle. 



(a) Of how many parts does it consist? 



(b) Is it entirely of bone or partly of cartilage? 



