488 MEMOIRS OF THE CARNEGIE MUSEUM 
mm. long. The smallest female with eggs or young is from New Jersey (Princeton), 
and is 48 mm. long. From the eastern part of our state I have seen none smaller 
than 55 mm. long, and in the western part the minimum is 59 mm. in length. 
This is considerably above the minimum size of sexually mature specimens of C. 
obscurus and agrees better with C. diogenes. 
In one case I have been able to observe the increase in size which takes place 
upon moulting. On July 11, 1905, I found at Tionesta, Forest County, a female 
in the act of shedding, and succeeded in keeping her alive till the new shell was 
hard enough to be measured. ‘The old shell was 32 mm. long, and the new one 36 
mm. in length. In this case the crawfish withdrew from the old shell through a 
crack that appeared on the dorsal side between the carapace and the abdomen. 
We have seen above that the regular seasonal cycle observed in the river-species 
is probably due to the regular and considerable changes of temperature taking place 
in the rivers. C. barton lives in small streams, which generally are much cooler in 
summer than the larger ones, and this apparently explains the difference in the 
seasonal history. The temperature conditions under which C. bartoni is found, are 
more uniform throughout the year, and consequently no regular seasonal periods 
in the life are observed. 
No previous observations on this species have been published, except William- 
son’s note (1899, p. 47), that this species was found with young under the abdomen 
on March 28, 1899, at Columbus, Ohio. This lack of information is rather singular, 
considering the extreme abundance of this form in the eastern part of the country. 
Cambarus bartoni robustus very likely is identical in its life-history with the 
typical form. I have made observations at only a limited number of dates, but 
they tend to show that there are no marked seasonal periods. 
The following dates for the capture of males of the first form are at hand: May 
27, 1904; July 11, 1905; August 22, 1905; September 18, 1900 (Atkinson collec- 
tion); September 30, 1905; October 4, 1904; October 6, 1904; November 14, 1903 
(Mus. Oberlin). The smallest male of the first form measures 63 mm. in length. 
Males of the second form were taken in the months of May, June, July, August, 
September, and October. They were abundant in every case, considering the number 
of specimens secured. 
Copulation was never observed. A female with eggs was found on July 11, 
1905, at Spartansburg, Crawford County. It was 84 mm. long, and the number of 
eggs was 228, more than twice the number of those usually observed in the typical 
C. barton. Young specimens, less than 20 mm. long, were taken on May 27, 1904 
(18 mm.); and were numerous in a lot collected by Miss G. Kinzer on August 27, 
1905 (9 to 16 mm.). 
