HARRIS : CRAYFISHES GENUS CAMBARUS. 163 



Under this head are to be placed only the species which show 

 a more special dependence upon this method of life for their 

 ability to live in a given territory. It seems not unreasonable 

 to suppose that most, if not ail, the stream-inhabiting species 

 dig short burrows into the banks more or less frequently, at 

 least in certain localities. 



The following species are those which seem to be most de- 

 pendent on the burrowing habit : C. diogenes, C. gracilis, C. 

 carolinus, C. argillicola, C. simulans, and C. immunis. 



C. diogenes has well been characterized as preeminently a 

 burrowing species, and, owing to its range of distribution 

 and peculiarities of its habits as compared with other species 

 inhabiting the same localities, more observations have been 

 made on this than any other form. Its presence is usually 

 indicated in the low places, where it is most frequently found by 

 the large number of mud "chimneys," sometimes scattered 

 over many acres, about a foot in height, radiating from some 

 sluggish stream, ditch, brook, or lower, moister portion of the 

 area, the animals being often found at a considerable distance 

 from any permanent body of water. Of the other species, C. 

 gracilis seems to be as typically a burrowing species as C. diog- 

 enes, being generally reported as an inhabitant of prairie re- 

 gions. Adults are to be found in stagnant ponds only in early 

 spring, only one exception being noted. While the burrows 

 are frequently found a long distance from any permanent 

 water, C. simulans has been reported from streams and ponds 

 and from burrows in a slough. C. immunis is recorded mostly 

 from stagnant ponds, resorting to burrowing upon the drying 

 up of these. I have never taken it in running streams. For 

 C. argillicola and C. carolinus the character of the habitat has 

 not been described. 



The chimney of C. diogenes has a maximum height of one 

 foot, but is usually lower, is circularly pyramidal in shape, 

 often somewhat higher than broad, the most remarkable differ- 

 ence being that of chimneys two inches in diameter and eight- 

 to eleven inches in height observed on the sloping side of a 

 ditch, by Abbott, who states that those found in meadows at a 

 distance from running water were invariably broader at the 

 base and not so high as those located near running water. 

 Tarr records exceptional cases where the burrows were in 



