1917] The Ottawa Naturalist 131 



I shall be very glad to receive any information concerning our 

 crayfishes or to assist anyone in the identification of specimens. When- 

 ever possible, specimens should be kept, together with records of the 

 locality and habits. 



All our crayfishes east of the Rocky Mountains belong to the 

 genus Cambarus, and we have at least eight species. The most inter- 

 esting ones are those that dig out burrows for themselves in the mud. 

 The material excavated is usually left at the opening of the hole as a 

 'chimney' of mud, which may be several inches in height. These 

 'chimneys' are frequently seen in low ground or on the banks of 

 streams. 



Recently I took occasion to investigate some of these burrows that 

 are quite abundant in the clay banks of the Twenty-Mile Creek, near 

 Tintern, in the Niagara Peninsula. The species that inhabits these 

 burrows proved to be C. immunis, which has not previously been 

 recorded from Canada. It is abundant in Ohio, southern Michigan, 

 and farther south and west. The present record places it in the 

 drainage area of Lake Ontario. 



All the specimens very evidently belonged to C. immunis, but 

 without exception they showed the presence of small lateral rostral 

 spines, which are only occasionally found in this species. In this 

 respect they agree with Faxon's variety spiuirostris. The excavation 

 at the base of the movable finger of the large claw was not invariably 

 present, being absent on one or other side in three specimens (two 

 males and one female). This species is most easily recognized by the 

 condition of the first pair of abdominal legs of the male. The two 

 branches of each leg are long and slender and curved so as to form at 

 least one quarter of a circle. 



The banks of the stream, where the burrows were situated, were 

 of a stiff blue clay. I believe that the stream never becomes wholly 

 dry. There is not then the same necessity for the crayfish to burrow, as 

 in the case of those inhabiting swamps and pools that become dry in 

 the summer months. Ponds and ditches of this sort are given as the 

 usual habitat of this species.* 



None of the burrows showed well-formed chimneys when I 

 examined the spot (September). They had apparently been destroyed 

 by passing animals or by the weather. The burrows were not built 

 in any regular fashion, but varied greatly. Each had either one or 

 several openings. The openings were sometimes all on the bank above 

 water, at other times some above and some below, and apparently, 

 sometimes all below. The level of the water varies during the season 

 and at times all the openings would probably be exposed. 



The length of the burrows varied from half a foot to several feet. 

 Sometimes they were nearly straight, but usually they were quite 



*See Harris, Amer. Natural., vol. 35, p. 187. 



