THE FROG 



A LABORATORY GUIDE 



INTRODUCTION 



The frog is a tailless amphibian vertebrate. Its exact 

 position in the system of classification is indicated below: 



Phylum: Chordata, 



Sub-phylum: Vertebrata, 

 Super-class: Tetrapoda, . 

 Class: Amphibia, 

 Sub-class : Lissamphibia, 

 Order: Anura, 

 Family: Ranidse, 

 Genus: Rana. 



One hundred and ninety-five species of this genus ^ have 

 been described, twenty-one of which are native to North 

 America. Of the latter the most common species is Rana 

 pipiens, the leopard frog, upon the anatomy of which these 

 directions are based. The largest species is the bullfrog, 

 Rana catesbiana, and for this reason a more desirable 

 form for laboratory work. The dissections here described 

 have been repeated upon the bullfrog, and any striking 

 divergences are noted. The latest key to the American 

 species is contained in Boulenger's Monograph of the Amer- 

 ican Frogs of the Genus Rana. It should be noted that 

 this author uses the specific name halecina instead of the 



*The tree frog and the toad belong to different genera although 

 members of the same order. 



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