Sixty-five were taken in the Cisco Lake Region and 19 in Ontonagon County, near Gogebic Lake. It is most abundant in grassy and sedgy meadows and in open bogs, though it is found rarely in swamps and tree-covered bogs. The individual listed from the arbor-vitae swamp was taken in a young growth of arbor-vitae, black spruce, hemlock, and many alders, and not in typical arbor-vitae swamp habitat. Of the 17 listed from the shrub stage, one was taken in a wet, sedgy part of a shrub-covered burn at Poor Lake, and the others were secured in the shrub and grass clearing around the camp house on Lindsley Lake. Of ten females examined, July 10 to September 5, one contained 3 embryos, one 4 embryos, and two 5 embryos each. September 5 was the last date on which embryos were found. The three embryos found on the last date were each 23 mm. in length and together they weighed 8.5 grams, which was 26 per cent of the weight of the mother with the embryos removed. Both adults and immature young were seen moving about, and were also trapped in broad daylight, but it is more active in the evening just before sunset. A captive juvenile was placed July 19 in a large tub with an adult female, which might have been its mother, for both were taken on succeeding days in the same trap. The young one immediately tried to nurse, but was severely bitten and driven away, though it made numerous unsuccessful attempts later. When approaching the old female the baby frequently gave a high-pitched squeak, and the old female replied by a hoarse squeak, evidently of warning, for the young one was bitten when it approached in defiance of the warning note and threatening attitude of the adult. The baby evidently had been weaned, and the old female was found to contain five large embryos. _Ondatra zibethica zibethica._ Muskrat. Forest--shore, 5. Water lily, 1. Pondweed, 2. Willow-thicket, signs. Muskrats are numerous in the Cisco Lake Region, and five specimens were taken. Near Little Girl's Point one was seen swimming in a small stream. At the mouth of Merriweather Creek on Gogebic Lake signs were noted in a willow thicket, and muskrats were reported numerous in the region. An adult female trapped July 6 at Fish-hawk Lake contained six large embryos; another female taken July 10 contained no embryos, but the mammae were filled with milk; and two females taken July 26 contained no embryos. In the Cisco Lake Region broken mussel shells were abundant in the muskrat runways along the shores. Remains of pondweeds were also frequently found in the runways, and a quantity of leaves with a few heads containing flowers and seeds collected July 8 were identified by E. A. Bessey as _Potamogeton richardsonii_. _Zapus hudsonius hudsonius._ Jumping-mouse.