When we arrived in the Cisco Lake Region in late June young and subadults were abundant, many of the female subadults, as well as the adults, carrying embryos. Embryos were found throughout the summer up to August 25. Of females containing embryos, five had 4 embryos each, ten females 5 embryos each, nine females 6 embryos each, and one female 8 embryos. _Synaptomys cooperi fatuus._ Lemming-vole. Tall-sedge, 1. Black spruce--tamarack bog, 2. Wet hardwood forest, 1. Dry hardwood forest, 1. In the Cisco Lake Region an adult female was taken in dry hardwood forest near Fish-hawk Lake June 28, 1920. It contained 6 embryos each 21 mm. long. A juvenile was trapped July 26 on top a log in the tall sedges at Mud Lake. The log bridged over a particularly wet part of the marshy sedges and was at the edge of the hardwood forest. Two other juveniles were taken the next day, one in a small black spruce log, and the other in wet hardwood forest at the edge of the same bog. In Ontonagon County near Gogebic Lake a subadult male was taken September 5 in a large black spruce bog. _Evotomys gapperi gapperi._ Red-backed vole. Black ash swamp, 2. Black spruce--tamarack bog, 6. Arbor-vitae swamp, 2. Hemlock forest, 5. White pine forest, 2. Wet hardwood forest, 18. Dry hardwood forest, 17. Shrub stage, 5. Paper birch--aspen stage, 3. Thirty were taken in the Cisco Lake Region, 10 at the Little Girl's Point camp, and 20 near Gogebic Lake in Ontonagon County. It was most common in the forests. Two individuals recorded from the arbor-vitae swamp were taken in a mixed swamp of small arbor-vitae, black spruce, and hemlock with many alders, this situation probably forming a stage in the succession following a beaver meadow. Also, one of the specimens recorded from the paper birch--aspen stage was taken in an open stand of old paper birches with a forest floor of grass, conditions not typical of the stage. Of 13 females examined from June to August, two contained 4 embryos each, two 5 embryos each, and two 6 embryos each. August 14, at Little Girl's Point, was the last date on which embryos were found. The species is somewhat diurnal. Several times one was seen in daylight about the camp in the Cisco Lake Region, and several were trapped during daylight hours. A captive was fond of tender grass blades, but refused the harder stems. In eating he sat up on the hind feet and handled the food with the fore feet. An immature male taken August 8 near Little Girl's Point had a considerable infestation of seed ticks on the posterior lobes of both ears. _Microtus pennsylvanicus pennsylvanicus._ Meadow vole. Mud-flat, 6. Tall-sedge, 28. Grassy-meadow, 6. Black ash swamp, 1. Arbor-vitae swamp, 1. Leather leaf bog, 15. Sphagnum bog, 9. Black spruce--tamarack bog, 1. Shrub stage, 17.