ORTMANN: THE CRAWFISHES OF THE STATE OF PENNSYLVANIA 483 
for the mating time. This, however, needs further investigation, and possibly, if 
found to be the case, may, nevertheless, not be the general rule. 
In no other part of the year were similar observations made, and this fixes the 
mating season for the months of August, September, October, and November,” agree- 
ing with what we have observed in the case of C. obscwrus. 
Thus we see that the seasonal cycle in the life of C. diogenes corresponds closely 
to that of the river-species. ‘The only difference is in the time when sexual ma- 
turity is reached, and it seems that in the case of C. diogenes this does not occur 
earlier than at the end of the second summer. Whether this influences the dura- 
tion of life is not known. Nevertheless the fact. that this species frequently, or even 
regularly, reaches a size superior to that of C. obscwrus, specimens of over 90 mm. in 
length being quite often found, suggests that this crawfish may live more than three 
years, possibly four or five. 
The resemblance of the life-history of this burrowing form to that of the river 
species is due, I believe, in large part to the similarity of conditions of temperature. 
As has been stated, C. diogenes lives near stagnant water and swamps, in places 
where there is generally not much fresh and cool water, although such places are 
not strictly avoided, and where the temperature of the water is subject to consider- 
able seasonal changes. In winter and spring the water in the holes is rather cool 
(43° Fahr. on March 23, 1905, in Nine-Mile Run), while in midsummer it becomes 
when stagnant, almost lukewarm. 
The above observations are in part at variance with those made by previous 
writers on the same species. Girard (1852, p. 88), near Washington, D. C., found 
females with eggs in March and April, which agrees with our dates, making allow- 
ance for the difference of climate between Washington and western Pennsylvania. 
Girard also noticed the fact that as a rule only one individual was found in each 
hole and mentions as an exception that in one burrow a male and a female were 
found together. However, he neglects to tell the exact date of this find (his obser- 
vations were chiefly made in spring). In one case, he says that a male was seen 
walking over the surface of the ground, as he believes, in search of the female. 
But in this instance also no date is given. 
Tarr (1884, p. 127) never found male and female together (in May, near Wash- 
ington), and always only one individual in each burrow, and he never found speci- 
mens outside of the holes.” He further believes that the burrowing crawfishes re- 
™ It possibly extends further into the winter, asin the case of the other species discussed. 
78 Although I have myself never seen a specimen of (C. diogenes walking over the ground, this must sometimes oc- 
cur, for males and females must come together in the mating season, and the holes do not communicate underground. 
According to Williamson (1901, p. 12), C. diogenes and C. monongalensis are nocturnal, and that they come out of their 
holes at night is shown by the fact that Mr. Rhoads captured some of them in traps set out over night for rodents. 
