214 Proceedings of Indiana Academy of Science 



species inhabiting all the northern part of the state". According to 

 Cory (1) the region under consideration is in the area of intergradation 

 of Mephitis mesomelas aria with M. ni. putida. A. H. Howell of the 

 Biological Survey has identified the two skulls given me as Mephitis nigra. 



Northern deer mouse {Peromysciis leucopus noveboracensis 

 Fischer) : This deer mouse is the commonest mammal in the region. 

 It was found in eveiy situation except in the low dunes along the lake 

 front where it appears to be replaced by the Baird deer mouse. The 

 percentage of traps holding deer mice ranged from 10 to 40 a night 

 except when the traps were placed in the fore dunes. Of the three baits 

 employed, rolled oats, peanut butter, and bacon, the latter seemed to be 

 the most effective. Several were taken in larger traps baited with apple 

 and set for squirrels and chipmunks. They were quite common about 

 our tent and helped themselves to exposed food. In addition to these 

 taken opposite Mineral Springs, one of this species was taken in a wooded 

 dune opposite Furnessville in 1921. 



Most of the adult males were in a rather bright yellowish pelage 

 although three or four had a short-haired coat of a sort of house mouse 

 gray. In the case of the females about half were in a bright and yel- 

 lowish pelage while the rest were in a short-haired house mouse gray 

 coat. Only three young specimens in a "blue" pelage were saved. Two 

 of these show an incoming yellowish coat on the sides. 



Three stages of development are represented among the specimens 

 collected, breeding adults, animals which have reached adult size and 

 coloration but not yet breeding, and young specimens in the "blue" coat. 

 In addition to these very immature young were noted. Of 18 mature 

 females all were apparently nursing young, none being pregnant. The 

 impression was gained that reproduction was carried on at regular inter- 

 vals and simultaneously by nearly all the mice. On the spot where our 

 tent was placed another party had previously camped leaving much food 

 around and many pasteboard boxes. On our arrival, there was noticed 

 in one of these boxes a Peromyscus nest, made of torn bits of paper after 

 the manner of house mice. It contained several young covered with hair 

 but unable to walk. On examining the nest a few hours later it was 

 found the young had been carried away. As the previous occupants of 

 the site had left Sept. 4 and we had come there Sept. 26, the mice had 

 evidently built the nest and reared young of small size in the course of 

 three weeks. The mammae are pectoral 1/1, inguinal 2/2=6. 



In subterranean runways in which traps were placed for pine voles, 

 deer mice were so often taken as to make one wonder if some of these 

 runways may not have been made by them. In some of the interdunal 

 meadows which had been quite wet or even covered with water earlier 

 in the season were numerous holes apparently the work of crayfi.sh 

 though only rarely was anything suggesting a "chimney" seen. Traps 

 set about these holes frequently yielded northern deer mice, some being 

 caught in such a manner as to indicate that the "animal had been in the 

 burrow at which the trap was placed. Once a crayfish was caught in a 

 trap placed at these burrows. W. D. Richardson states that deer mice 

 frequently enter his cottage and have the same activities as house mice 

 in cities. 



