472 MEMOIRS OF THE CARNEGIE MUSEUM 
form, 81 mm. long, which was lying concealed under a rock in the usual position. 
It was absolutely perfect, without blemish, and with an old, very dirty shell, thus 
clearly showing that it had gone through the previous winter. This specimen was 
barely alive and to all appearances in a dying condition. A similar instance was 
noticed on April 24, 1905, in Wheeling Creek, Elm Grove, West Virginia. Here a 
large male of the first form (84 mm. long) was found showing no signs of injury, in 
fact in very beautiful condition, but barely able to move. It was kept in water, 
but was dead the next day, while other specimens collected together with it were 
none the worse for their journey to Pittsburgh. Thus it seems that the conclusion 
is Justified that the largest males of the first form, after having in the autumn at- 
tained a certain maximum size, which may be different according to conditions, but 
may be said in general to be about 80 mm. in length, go through the winter, but do 
not moult again, and die a natural death in spring.” 
The latest dates at which I found males of the first form in spring are as fol- 
lows: June 6, 1904, Linesville (the case just mentioned), May 30, 1904, at Waynes- 
burg, Greene County; May 25, 1905, Alleghany River, Mosgrove, Armstrong 
County. After the beginning of June, all through the month, and through a large 
part of July, no males of the first form have been found, and through the remainder 
of July they are scarce. (See below.) 
The eggs carried by the females hatch at the end of May and the beginning of 
June. I found young under the abdomen of the mother on May 30, 1904, on June 
5, 1906, and on June 6, 1904. The period during which the young stay with the 
mother seems to be short. On May 25, 1905, I found eggs, not yet hatched. From 
June 15, 1905, onward all through the remainder of the year I never observed a 
female with eggs or young. Between these two dates I have only four records, May 
00, 1904, June 2, 1905, June 5, 1906 and June 6, 1904, in three of which the pres- 
ence of young ones with the mother was shown. ‘Thus the period when young are 
found under the abdomen of the mother is very likely the end of May and first half 
of June (about three weeks), and the young crawfishes probably do not remain with 
the mother much longer than a week. ieee 
Throughout June and part of July no males of the first form are present; all 
males are of the second form, but they are not very large, reaching a maximum size 
of only between 60 and 70 mm. ‘The females have got rid of their progeny, and 
begin to moult. The old females may die like the old males, but I have no evi- 
dence on this point, except as drawn from analogy to the males, and the fact that 
TOA great mortality of malesin spring (after copulation in captivity) has been observed by Andrews (1904, p. 
175) in C. limosus. 
