A FROG 165 



SUBPHYLUM VERTEBRATA 



Class: Amphibia. Order: Salientia 

 A FROG 



The following descriptions will enable the student to identify 

 the commonest species of frogs.^ 



Rana pipiens, the leopard frog. Green or brown, with large black blotches 

 edged with white or yellow which lie in two irregular rows on the back ; legs 

 barred above ; belly pearly or yellowish ; length about 2| inches ; lives in 

 marshes and wet places or in the grass. 



Rana palustris, the pickerel frog. Brown or greenish, with several rows 

 of oblong square blotches on back and sides ; length about 3 inches ; com- 

 mon in cold springs or streams or in the grass. 



Rana clamitans, the green, or spring, frog. Green or brown, with rounded 

 spots all over the back ; legs with several cross bands ; beneath, pure white ; 

 length 3 inches ; lives in ponds and streams. 



Rana catesbeiana, the bullfrog. Green or brown, with faint dark spots 

 above ; head often bright green ; beneath, with pale blotches ; length 5 to 

 8 inches ; lives in ponds and streams. 



Rana sylvatica, the wood frog. Pale reddish brown; head small and 

 pointed, with a dark band on each side between eye and arm; length 

 i^ inches ; lives in the woods and in the grass. 



Three specimens will be needed for a complete dissection of the 

 frog : one for the outer form and the greater part of the internal 

 organs, including the heart and the great blood vessels entering 

 and leaving it ; one for the other blood vessels ; and one for the 

 skeleton. A partial dissection can be made with a single specimen. 

 The animals should be preserved during the dissection in a 5 

 per cent solution of formalin or in cold storage. 



Place the animal (alive if possible) under a glass or in a dis- 

 secting pan and observe its form and color. The body is short 

 and compact, with a large head and mouth ; the hinder end is 

 characterized by the lack of a tail and by the great length of 

 the hind legs. The color is such as to adapt it to the environ- 



1 These descriptions have been modified from H. S. Pratt's ''Manual of the 

 Vertebrates of the United States." 



