12 University of Michigan 



The \vriters believe that the above table shows that the local 

 distribution of the species is principally controlled by the habitat 

 preferences. Among the land forms those preferring a fine 

 soil are principally basin floor forms, the saxicolous forms are 

 almost exclusively mountain species, and those with general 

 habits have a general distribution. The distribution of the 

 amphibious forms is determined by the permanence of the 

 streams and the degree to which the species are dependent 

 upon the presence of water. The limnicolous and paludicolous 

 forms are found only on the basin floor, while those which can 

 endure dry habitats for most of the year also occur in the 

 mountains. As yet unexplained is the apparent confinement 

 of several species to single localities. 



List of Species. 



Eighteen reptiles and amphibians were found in the region. 

 As previously stated the habits, distribution, and characteristics 

 of the forms were studied, and these are summarized in the 

 following pages. 



Rana pipiens Schreber. 



Common in the Humboldt Valley. 



The specimens show little variation from Dickerson's (The 

 Frog Book, 171) description. The ground color in life was 

 almost invariably dark gray, only one green specimen being se- 

 cured ; small and recently transformed individuals were grayish 

 brown in color with small, round, dark brown spots. 



The leopard frog was the most common amphibian of the 

 region and a large series of specimens was secured. Small 

 frogs with tails longer than their bodies were frequently 

 observed hopping about in the grass around the ponds. Adults 

 were usually found in the water of stagnant pools or on their 

 banks ; only occasionally were they observed in running water. 



