486 MEMOIRS OF THE CARNEGIE MUSEUM 
locations in the neighborhood. Thus this case must be regarded as exceptional, not 
as a regular or normal episode in the life of the species. 
5. Cambarus barton. and Cambarus bartoni robustus. 
In all the species discussed so far we have found a regular seasonal period in the 
life-history, marked chiefly by a distinct mating-season in fall, a spawning-season in 
spring, and a season in early summer when no males of the first form are present. 
But it is entirely different in the case of C. barton. In this species none of these 
seasons is recognizable. 
As to the mating period, I have observations on only two dates. On May 27, 
1904, I found a couple 7m copula in Squaw Run. Here I was able to make a close 
observation. The act of copulation is similar to that in the case of C. limosus, as 
described by Andrews (1904), but the male does not take hold of the anterior walk- 
ing feet of the female with its chelee, and its second|pereiopods are clasped around 
the carapace of the latter, lying in the cervical groove, and almost touching each 
other on the back of the female. In this case it was the fifth pereiopod of the left 
side, which was stretched across the sternum in order to elevate the copulatory 
organs. The male of this couple was 67 mm. long, the female 73 mm. long. The 
other observation occurred on October 6, 1905, when I found two couples together 
at Weskit, near Kittanning. The male of the first couple was 63.5 mm., the female 
59mm. long. In the other couple both male and female were 63 mm. long. Both 
couples separated when captured, and thus I cannot give particulars. 
These two dates are so far remote from each other that it seems hardly probable 
that they belong to one and the same breeding season. It is possible that one of 
them is exceptional, but I have no means of deciding this. On the other hand, as 
we shall see presently, spawning takes place at such different times of the year 
that very likely the mating-season is also irregular. 
Females with eggs have been found on the following dates: July 6, 1905; July 
10, 1905 ; July 20, 1904; July 29, 1905; August 1, 1905; August 9, 1904; August 10, 
1905. The number of eggs was between seven and one hundred and thirty-three, 
the smallest number being found in the smallest individual, 59 mm. long. In ad- 
dition I took a number of females with young under the abdomen. ‘The following 
records are at hand. At Princeton, New Jersey, in February, 1898. The exact 
date is not recorded, but it was toward the end of the month. The length of the 
female was 48 mm., the number of the young was ten.” Further: March 31, 1905; 
6° This number is unreliable, but represents as many as were secured. In some cases quite a number of the young 
dropped off when the mother was captured. 
