ORTMANN: THE CRAWFISHES OF THE STATE OF PENNSYLVANIA 479 
Andrews (1904, p. 166) places the normal mating season in the months of February, 
March, and the beginning of April, and says that there seems to be an autumnal 
pairing (October, November) “in place of or in addition to” the spring pairing. I 
believe, however, that the autumnal pairing is the normal one, which may be 
extended through the winter. Indeed I have observed it in January, but only in 
specimens kept in captivity. Since Andrews’ observations were made in the labora- 
tory, it appears probable that the mating may be continued or repeated under excep- 
tional conditions such as are offered in captivity, but that this is not normal. In 
C. obscurus I am positive that under natural conditions copulation does not take 
place in March and April. 
The time of spawning, as observed by Andrews (1904, p. 176) agrees well with 
our records (end of March and April), also the time of hatching (/. ¢., p. 187), late 
in May. 
As to sexual maturity, Andrews did not gather facts to show that females are 
mature and oviposit at the end of the first year (1904, p. 206), although he observed 
copulation at the end of the first summer. I observed, on November 4, 1905, copu- 
lation taking place in specimens less than 45 mm. long, and found females “in 
berry” of the size of 50 and 45 mm. (Cumberland, May 9, 1905). Since the same 
fact has been observed in the case of C. obscwrus it is certain that males as well as 
females are sexually mature at the end of the first summer, and that the sexual 
union is effective, the females spawning the following spring. However, in such 
small females the number of eggs is generally very small (fifty or less). 
Thus it seems that C. limosus agrees perfectly with C. obscwrws in its life-history, 
and that the only marked difference from Andrews’ account concerns the mating 
season. ‘This is however apparently due to the fact that Andrews’ observations were 
made in the laboratory. The explanation for this is very likely to be sought in the 
temperature conditions. ‘The water used in tanks in laboratories has generally a 
rather uniform temperature throughout the year, while under natural conditions the 
temperature of ponds, rivers, and streams varies considerably in summer and winter. 
I made a few observations with reference to C. obscwrus. In January, under the ice, 
the water is near the freezing point, say about 35° F.; on April 6, when females 
were found spawning, the temperature of Thorn Creek, Butler County, was 45° F. 
On May 1 the temperature of Grave Creek, Marshall County, West Virginia, was 
66° F. and spring moulting was going on. In midsummer I observed a temperature 
of 82° F. in Bates Fork, Greene County, on July 24, and a temperature of 78° F. in 
the Ohio, at Ambridge in Beaver County on August 24. 
This gives a range of from about 35 to 80 during the year, and I have no doubt 
