No. 441] HABITS OF CAMBARUS. 605 



Too much importance, it seems to me, has been attributed to 

 the chimney in discussions of the habits of Cambarus. While 

 the chimney is usually a very regular and well-built structure, it 

 is often found, in some species at least, as a more or less irreg- 

 ular heap of clay pellets, and so far as our present knowledge 

 extends, can hardly be regarded as anything more than the result 

 of the easiest method of disposing of the material removed in 

 excavating the burrow. On this point, however, further obser- 

 vations are desirable. The purpose of the sealing of the burrow 

 is not so clear. The prevention of material falling into the bur- 

 row from the surface and possibly (?) protection against enemies 

 may account for it. That the sealing is not a matter of the acci- 

 dental falling together of the upper edges of the chimney while 

 in a moist condition is evident from the fact that the opening is 

 sometimes filled to below the surface of the ground and, as some- 

 times happens, with clay of a different nature from that compos- 

 ing the rest of the chimney. * 



Concerning the purpose of burrowing there can now be no 

 question. Some species of Cambarus seem never to re^Brt to 

 the habit, in the restricted interpretation of the term, while 

 others, C. immunis, and, to a less extent, C. virilis, are inhab- 

 itants of ponds or streams and resort to burrowing only upon the 

 drying up of the ponds or the approach of winter, while C. Diog- 

 enes and C. gracilis have adopted this mode of life almost entirely, 

 being found in the open water during but a very small part of 

 the year. That the burrows are not for retreats while the eggs 

 are being hatched has been conclusively shown. That they 

 serve as a place of protection against enemies has been sug- 

 gested and while it cannot be stated that the burrowing species 

 are not better protected against animal enemies than are the 

 forms inhabiting open water this cannot be the primary purpose 

 of the burrow. The burrows are almost invariably described as 

 extending to the water in the soil, and while the water in the 



