32 IOWA ACADEMY OF SCIENCES. 



width, an ellipse; the trough is J^ inch deep, with holes near each end; these were 

 drilled from both sides with a conical instrument. The greatest depth of the 

 implement is 1,^4 inches, somewhat flattened on the convex edge over the holes. 



Through the kindness of Mr. Weir I am permitted to exhibit these relics to the 

 members of this Academy. 



SOME REASONS WHY FROGS ARE ABLE TO SURVIVE. 



BY OILMAN DKEW, OSKALOOSA. 



The Leopard frog [Rana halecina, Kahn) and allied species occur in con- 

 siderable numbers and have a wide geographical distribution. 



Being entirely defenseless, beset by enemies at every turn — fish, reptiles, 

 birds and mammals — as well as being cannibals among themselves, subject to 

 many diseases and the hardships of great extremes of temperature, they are, 

 withal, able to maintain their numbers. 



They are able to survive— first, on account of their activity and mode of 

 life, being equally at home on land and in water ; secondly, they are able to 

 resist great changes in temperature ; thirdly, they can go for many months 

 without food, and fourthly, they are very productive. 



Disturbed on land, they generally jump into the water, where they find a 

 hiding place and remain motionless unless danger approaches very near. 

 Pursued in water, they either dive among the rocks or into the mud, or in 

 some cases escape to the land. In either case, in localities where they have 

 not often been disturbed, they may easily be approached if all motions are 

 made slowly and carefully, but quick motions will generally cause alarm. 

 A frog can be most thoroughly alarmed, especially one that has lived for 

 some time in a region infested with snakes, by running a stick toward it, 

 causing the grass to rustle. In such a case, if not where it can immediately 

 plunge into the water, it executes a series of frantic leaps with great rapidity, 

 stopping only when at a considerable distance from the place of disturbance. 

 When disturbed in any other way, the same frog will seldom make more 

 than three or four jumps, and these are made with more deliberation. 



Living, as many frogs do, in a climate where the temperature for some 

 months is below the freezing point of water, and having no covering to pro- 

 tect.themselves against severe cold, they survive this part of the year in a 

 state of hibernation in the bottoms of the rivers and ponds, supposedly 

 buried in the mud or sand. Judging by the time frogs disappear from the 

 banks of streams, they seem to hibei-nate at about six to ten degrees C, and 

 by the time that the first hard freeze comes, they have disappeared, in gen- 

 eral, for the winter. In some cases, they may, during thaws, come out 

 before the general break-up in the spring, but not as a rule. For some time 

 before they finally hibernate, they spend the nights under water, probably 

 in a state resembling hibernation, coming out again during the warmer por- 

 tions of the day. 



In warm weather, a frog, when disturbed in the water, will generally 

 dive, remaining under water only two or three minutes. When they receive 



