316 RAMBLES ABOUT HOME. 



The pickerel-frog may be said to differ from the pre- 

 ceding in the number and position of a few spots on the 

 back : the herring-frog has the spots in two rows, while 

 in the pickerel-frog they are in four. This is the one 

 apparent difference, though there may be others not as 

 marked. This slight variation in color and markings is 

 constant and uniform, and it must have been brought 

 about by some potent cause, supposing that these and 

 our other frogs are derived from some ancestral type 

 which is at once like, yet unlike, the five species that now 

 frequent our meadows ; and no other supposition is ten- 

 able. 



I have tried in vain to detect some difference in habit, 

 or variation in date of appearance, or preference for dif- 

 ferent localities, of these two kinds of frogs ; but all in 

 vain. Where the one is, there we find the other also, 

 arid the two species even keep up their croakings in 

 concert. Possibly, there may be a little difference in 

 their voices ; but of this I am not sure. Of the fact, that 

 they belong to two species, there can be no doubt, and, as 

 this difference can not be one of color alone, it is idle to 

 suppose that we are acquainted with the full history of 

 their lives. This we shall never be until we discover 

 some action that is habitually performed by one and not 

 by the other, or until we discover some places that are 

 frequented by one and as carefully shunned by the other. 



What claims, it may be asked, have these frogs upon 

 us ? This is easily answered. They are not only great 

 checks upon an undue increase of insect life, but they are 

 also scavengers. They do not, it is true, wander about 

 the uplands in search of decaying animal-matter ; but in 

 the waters they frequent they consume much that would 

 otherwise render them impure. The minute larvre of 

 aquatic insects are destroyed by them in vast quantities, 



