1897.] NATURAL SCIENCES OF PHILADELPHIA. 29 



swamp grown up with Juncus and grasses. The temperature fell on 

 two nights when these were taken to near 32°, forming heavy frosts. 

 Their absence from my traps in the Walkill Valley and at Green- 

 wood Lake was undoubtedly due to the low temperature having 

 driven them all to their winter repose. A thick layer of yellow fat 

 completely covered the bodies of these Culver's Lake specimens, 

 adhering so firmly to the skin that it was very difficult to preserve 

 the specimens. 



16. Zapus insignis Miller. Woodland Jumping Mouse. 



I secured four beautiful specimens of this Zapus in woodland 

 along a small rocky stream connecting a rhododendron swamp with 

 Lake Hopatcong, near Nolan's Point. All were trapped close by 

 the water's edge, precisely as described by Mr. Miller in his later 

 account of the species. I have never taken this animal in open sit- 

 uations such as are preferred by its kinsman of the meadow.* The 

 most persistent trapping in likely places at Culver's and Greenwood 

 Lakes did not reveal the presence of insignis there. It seems prob- 

 able that it is more sensitive to frost than hudsonius and had gone 

 into winter quarters before my arrival at Culver's Lake. At Green- 

 wood Lake a dormant jumping mouse, evidently of this species from 

 the description given me by the finder, was dug out of a gravel 

 bank during my stay. I visited the spot, and from its situation in 

 deep woodland near a brook, I am morally sure it was insignis. The 

 narrator of the incident stated that he knew the meadow species 

 very well, but that this one was " much redder." These particulars 

 are given to show not only that insignis is found in Passaic County, 

 but to prove that it hibernates earlier than hudsonius. 



The presence of a persistent premolar in all other known species 

 of the genus as contrasted with its absence in Zapus insignis may 

 eventually entitle the latter to separate subgeneric rank. 



17. Castor canadensis Kuhl. American Beaver. 



Numerous localities in northern New Jersey are pointed out as 

 the traditional sites of beaver colonies. This animal was so early 

 exterminated in these places that I found it impossible to secure any 

 data relating to the time of their extinction. 



18. Arctomys monax (L.). Woodchuck; Ground Hog. 



Very abundant on the Delaware slope of the Kittatinny Mount- 

 ain ; less so in other localities named except at Lake Hopatcong. 

 No specimens were taken. 



