CAMBARUS. 75 
There elapsed some three or four minutes between each appearance ; but 
every time it came, it brought a ball of clay and deposited it in the manner 
I have described. About two fifths of the balls were not placed with suffi- 
cient care, and rolled down the outside of the chimney.” 
Dr. Abbott believes that the closing of the orifice of a chimney is merely 
the result of the accidental falling in of pellets from the rim, loosened 
perhaps by atmospheric moisture. In some localities where the burrowing 
crayfish abounds, there is a weather proverb to the effect that, when the 
crayfish closes the opening of his chimney in dry weather, there will be a 
rainfall within twenty-four hours. 
It is difficult to imagine the object of this crayfish in building these 
elaborate subterranean abodes. Further observations on the method of tun- 
nelling, on the winter habits of the animal, and on its mode of life during 
the breeding season, are much needed. 
The mud chimneys built by C. Diogenes were observed and figured long 
ago by Audubon (Birds of America, Plates 222, 586; 8vo ed., Plates 360, 
370), who describes the ingenious device whereby the White Ibis draws the 
crayfish from its retreat (Vol. VI. p. 57). 
In life C. Diogenes is olive-colored, reddish on the margins of the rostrum, 
the post-orbital ridges, and the margins of the abdominal somites ; chelie 
cream-colored within, fingers reddish. 
The largest specimen which I have seen from the East measures $84 mm. 
from the tip of the rostrum to the end of the telson. Specimens received 
from Illinois measure 111 mm. in length. 
According to Forbes and Bundy, C. Diogenes is one of the commonest 
species in Illinois and Wisconsin. 
27. Cambarus Nebrascensis. 
Cambarus Nebrascensis, Girarp, Proc. Acad. Nat. Sci. Phila., VI. 91, 1852. 
Cambarus Nebrascensis, HacEn, Ill. Cat. Mus. Comp. Zodl., No. III. p. 83,1870. (After Girard.) 
Cambarus Nebrascensis, Faxon, Proc, Amer. Acad. Arts and Sci., XX. 145,.1884. (After Girard. No de- 
scription.) 
“Rostrum intermediate in form between that of C. robustus and C. Dio- 
genes. Dorsal lines of suture of the carapace in close contiguity. Large 
claw nearly conical, giving to the species a very peculiar aspect. 
“ Locality. —Fort Pierre (Nebraska) ; collected in 1850 by Thaddeus Cul- 
bertson.” Girard. 
