74 A REVISION OF THE ASTACIDA. 
touch consists in shutting up the aperture. This is accomplished by means 
of several balls of mud, brought up from underneath, deposited temporarily 
on the edge of the chimney, and drawn back in close contiguity, so as to 
intercept all communication with the external world.” * 
Another account of the burrows and mounds of C. Diogenes, by R.S. 
Tarr, has recently been printed, with diagrams, in “ Nature,” Vol. XXX. 
p- 127, June 5, 1884.7 Mr. Tarr’s observations, like Girard’s, were made in 
the neighborhood of Washington. According to Mr. Tarr, the eggs hatch 
about the middle of May, while the parent is living within her burrow ; but 
Mr. P. R. Uhler tells me that during the period of incubation the female 
goes into pools, ditches, and quiet waters along the margin of overflowing 
creeks. Mr. Tarr believes that the chimneys result from the excavation 
of the burrow, without implying design on the part of the crayfish. Dr. 
C. C. Abbott,f on the contrary, is convinced that they are carefully designed, 
since they are often built on the steeply sloping banks of ditches, where 
the ejected balls of mud would surely roll into the ditch if they were re- 
garded by the crayfish simply as rejected matter. In fact, an artistic tower, 
only two inches in diameter and varying from eight tg eleven inches in 
height, is erected on the steep incline. In several such instances observed 
by Dr. Abbott the base of the tower was provided for by levelling the ground 
before the foundation pellets of mud were laid. Of a series of forty towers 
observed by Dr. Abbott on the banks of a ditch, not one, in his estimation, 
could have been the result of accident. 
As these pages are going through the press, I have received an article 
by Dr. Abbott,§ which states that his nephew, Mr. Jos. DeB. Abbott, has seen 
the crayfish engaged in building its chimney. The observation was made 
in the night by the light of a candle. The crayfish was seen to emerge 
partially from its burrow, bearing “on the back of its right claw a ball of 
clay mud which, by a dexterous tilt of the claw, was placed on the rim of the 
chimney. Then the crayfish remained perfectly quiet for a few seconds, 
when it suddenly doubled up and dropped to the bottom of its burrow. 
* Girard states that Mr. T. R. Peale informed him that he had observed mud chimneys, similar to those 
built by @. Diogenes, in New Grenada, along the Rio Magdalena, several hundred miles from the sea. This 
observation is of interest, as indicating the possible southward extension of Cambarus beyond the Isthmus of 
Panama. 
} “Habits of Burrowing Crayfishes in the United States.” 
¢ “Are the ‘Chimneys’ of Burrowing Crayfish designed?” Amer. Naturalist, Vol. XVIII. p. 1157, 
November, 1884. 
§ “Tow the Burrowing Crayfish works.” The Inland Monthly, Vol. I. pp. 31, 32, Columbus, Ohio, 
February, 1885. 
