THE REVISION OF THE ECHINI 95 



examine a great many beaver dams, both deserted and 

 still occupied. I collected a good many cuttings, chips, 

 etc., made as many observations of habits, measurements 

 of dams, canals, as my time would allow — just as I was 

 preparing to get my notes together I found in the " Na- 

 tion " a Review of your book on the beaver, and since 

 my return to civilized regions it was one of the first 

 things I read. As I wrote father, it had taken the wind 

 out of my sails completely and there was no necessity of 

 my doing anything further at present, as your experi- 

 ence and opportunities had been more ample than mine, 

 and had evidently left, as far as I can judge from first 

 examinations, but little and that of trifling importance, 

 to add to the natural history of tbe beaver. 



I have some observations as to the time which beavers 

 have inhabited the regions which may be accurate enough 

 to determine the length of life of this species in the dis- 

 trict, but my data are not yet in shape. Having passed 

 two winters up there, I find that the beavers are more 

 active during that time than you give them credit for. 

 This is not confined to periods of thawing, but during 

 the regular winter weather. I find also that they migrate 

 in large numbers during that time, and while walking 

 on snowshoes through the woods have come upon their 

 tracks in all directions at considerable distances from 

 their dams. In two cases I have followed their trails 

 and have come upon a pair of young beavers starting 

 their dam in a fresh locality. The beavers I observed 

 seemed much more shy than yours and the effect of 

 interfering with their dams, even in a small degree, 

 almost invariably resulted, if repeated two or three times, 

 in driving them off. I was very desirous of obtaining 

 photographs of some of their workings, but all my 



