188 THE AMERICAN NATURALIST. [Vor. XXXV. 
ponds in the early spring. I have always found them in the 
greatest abundance in ponds which became perfectly dry dur- 
ing the summer months, but where the crawfish go during this 
time I have never been able to ascertain. Doubtless great 
numbers of them are eaten by birds and other animals, and 
great numbers of them perish; yet by the next spring they 
are as abundant as ever and of about the same size." 
C. immunis is our most common species in Douglas County, 
Kansas, and is found in almost precisely the same habitat 
as reported above for Illinois, Indiana, Michigan, and Min- 
nesota. Roadside ditches and ponds in pastures are favo- 
rite places. In this county we have ponds in an old river 
bed which contain immense numbers of this species. These 
ponds are six to eighteen inches deep, depending upon the dry- 
ness of the season. They are very muddy and have usually in 
the shallower parts, which are apt to become dry during the 
summer, a rank growth of Polygonum and plants of like habit. 
From such a pond I took, one day in October, 1898, in com- 
pany with Mr. C. D. Bunker and another collector, about fifteen 
hundred specimens, of which only a very few were less than 
two and one-half inches in length. There were not more 
than a half dozen small specimens in the whole lot; in other 
ponds, however, I have made collections which showed almost 
all stages of development. In many of the ponds C. immunis 
seems to be the only species, but in others we find also 
C. gracilis Bundy and C. virilis Hagen (?), but these do not 
occur in nearly so great numbers as does C. immunis. 
According to my observations, C. immunis is a burrowing 
and, at least to a certain extent, a chimney-building species. 
Burrowing, however, appears to be only resorted to when there 
is danger of the drying up of the ponds or on the approach of 
winter. Lack of opportunity for examining the ponds in all 
different conditions without doubt accounts for the failure of 
Hubbard’ or Hay? to observe the burrowing habit of this spe- 
cies. Hay's suggestion of crawfish perishing upon the drying 
up of the ponds seems to me to be largely ungrounded, since 
I have never found any considerable numbers of dead ones in 
! Faxon, W. Loc. cit. 2 Hay, W. P. Loc. cit. 
