70 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
observations made on frogs of this species at Newton, Mass., are 
of interest psychologically. 
Several frogs living in a certain small muddy pond in a wood 
were persecuted by boys throwing stones at them. This made the 
frogs very shy, so that when anyone approached, they would 
quickly disappear among the dead leaves at the bottom. After 
having frightened them in this way, I have sometimes sat down 
and waited for ten minutes or so, till they again appeared, break¬ 
ing the surface of the water without a ripple, and sitting motion¬ 
less as before. After they had remained thus for a few minutes, 
I threw small pebbles into the water near them, but they paid no 
attention whatever. Finally I threw good-sized stones at them, 
which splashed the water over them and even made them rock on 
the small waves, but even then, they would often remain where they 
were, apparently suspecting no danger. As soon, however, as I 
arose and walked near them they saw me and retreated beneath the 
surface. I have seen painted tortoises (Chrysemys picta ) show 
the same indifference to stones falling near them, provided they 
saw no movements to indicate danger. It would thus seem, that 
these animals have learned to associate danger with the approach of 
man, but after they have assured themselves that the coast is clear 
they will not easily take fright unless they are warned of danger 
by seeing some suspicious movement. 
These frogs do not seem to feed much during the day, but at 
such times sit basking i n the sun. Towards evening; they become 
active, and may be heard every now and then splashing in the 
water as they plunge after some passing insect. 
10. Rana catesbiaista Shaw. Bull Frog. 
Rather common in the small ponds on the intervales, whence its 
loud notes may be heard well into July. In Echo Lake, this frog 
is very common, and great numbers of young ones were found 
there during July. These were in various stages of development, 
most of them having acquired all four legs, but still retaining the 
greater part of the tail. On one bright sunny day in July, I found 
a great many under pieces of wood tying in the water near shore, 
and saw others swimming along the edge of the lake. This frog, 
with the exception of a very few R. palustris , seems to be the 
only frog in the lake. 
I caught one large specimen from a small muddy pond, and, 
taking it home, kept it for a while in clear water in a large white 
