1884.] NATURAL SCIENCES OP PHILADELPHIA. 65 



belt of smooth soil generally surrounds the base of a hill (see 

 figures above), on the outer margin of which (in old formicaries 

 especially) springs up a circle of a tall, stiff, thick-stalked grass, 

 such as always grows upon the heaps which the badger throws 

 up when burrowing after gophers. This grass remains green 

 until late in the fall, and when the dry prairie is swept by the 

 flames, it stands as a breastwork around about the mounds, often 

 deflecting the fire or greatly modifying its destructive effects. In 

 this way the formicaries are kept safe within the girdling ranks 

 of the friendly plant. 



Concerning the effects upon the ants of the severe winters of 

 Dakota, I could get no information ; but as the frost is said to 

 penetrate to the distance of seven feet, I conjecture that the 

 insects must carry their galleries below that depth, though they 

 are doubtless capable of enduring a very low temperature. The 

 surface is thickly covered with snow during winter months, and 

 it is probable that the ants then are in a semi-torpid state. They 

 reappear in the spring with vegetation. It is a difficult matter to 

 exterminate a colony by artificial means. 



The saying is current among the people of this section, reported 

 both by Dr. De Puy and Mr. Russell, that if one wants to dig a 

 well he will find water by going down through an ant-hill. I 

 heard the same proverb in Texas applied to the Agricultural and 

 especially to the Cutting ants. My experience is that these 

 popular traditions often have some basis of truth, but in this case 

 I give little credit to the notion. As these Dakota ant-hills are 

 scattered over the whole rolling prairie country at not very great 

 intervals, tbere certainly can be no likelihood that the people will 

 ever lack water, as a well might be successfully sunk anywhere, 

 according to emmet indications. A rule of this sort could not be 

 worth much in such a country. In Texas the notion is based 

 upon a supposed necessity for the ants to have access to under- 

 ground sources of water. 



