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. obscurus. 



Thus we see that the sea.sonal C3'cle in the life of C. dinrjcnes corresponds closely 

 to that of the river-species. The only difference is in tlie 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. obsciirus, 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, (.'. 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 v>inter 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 witli those made by previous 

 writers on the same species. Girard (185"i, p. 88), near Washington, D. ('., 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 notised 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 onl}' one individual in each burrow, and he never fountl .'spcci- 

 mens outside of the holes.'* lie further believes that the burrowing crawlishes re- 



" It possibly extends further iuto the winter, a.sin the ca.se of tlie other species iliscussed. 



" Although I have myself never seen a speciiucn of C. dwijrnn walking over ihe Kruiiiul, this must sometimes oc- 

 cur, for males and females must come tojjether in the mating; season, and the liohs do not communicate undrrcround. 

 .VccordiuK to William.'ion ( 1901, p. 12), C. diitgrne.i and ('. miiiwiignlriisiii are nocturnal, and that they come out of their 

 holes at night is shown by the fact that Mr. Khoada captured some of them in tniiw set out o\er night for roilents. 



