12 Annals of thk. Carnegie Museum. 



age constructed much more neatly by du{i:;eiies than by dnbius. The 

 habits of the former species have been carefully described by a num- 

 ber of observers. The burrows of diibiiis are generally more intricate 

 than those of dio^^e/ies. In both species the burrows occupied by 

 smaller individuals are usually a simple tunnel ending in a small pocket 

 which is placed at such a depth that it is filled with water. On Sep- 

 tember 24, 1898, one burrow at Fern Hollow, typical of those in- 

 habited by large individuals of diihiiis, contained an adult female and 

 47 young. The chimney was about three inches high, broad and 

 flattened and not composed of compact pellets as is usually the case 

 with d/oi^encs, and was closed at the top. The burrow was circular 

 and al)Out one and one-half inches in diameter with the sides smooth. 

 It ran, in a slightly oblique direction, with two or three turns, to a 

 depth of about fourteen inches where it ended in a pocket, half filled 

 with water which contained the mother and young. The capacity of 

 this pocket exceeded a pint. A number of passages led off from the 

 main tunnel. One of these branched, one part going to the surface 

 and ending in a low, closed chimney, the other running to within an 

 inch of the surface, where it ended. The remaining side tunnels, one 

 of which branched, ended in ])Ockets. The capacity of one of these 

 was not less than a quart. The entrance and exit to the pockets were 

 by the same tunnel. These i)ockets are certainly, in the case of this 

 species, not formed accidentally as a result of deepening the tunnels 

 from time to time, when this becomes necessary in order to reach the 

 water, but are built for some purpose, as is shown by their size and 

 form and by the fact that in many cases the entrance to the pocket is 

 from below and not from above, as would be the case had the pocket 

 or chamber originally been the bottom of a tunnel. At some places 

 in Fern Hollow the ground was fairly honey-combed with burrows. 

 Starting from one chimney it was sometimes possible, by tracing the 

 many branches, to prove that several chimneys had tunnels which were 

 connected with each other. Like diogenes this species is nocturnal. 

 Mr. S. N. Rhoads had traps set for small mammals in Fern Hollow, 

 and on several occasions, when visiting these traps in the morning, he 

 found specimens of this crayfish in them. The bait used in these 

 traps was a raisin, with a pinch of oatmeal scattered about. In this 

 locality the color of the specimens of this species during life is usually 

 a clear bright blue below, with the articulations pale. A few individ- 

 uals had the blue on the carapace largely replaced by dull brown. 



