I have several times found nests in meadows and cultivated fields. The nest is built in a deep form and is lined with fur from the mother's body and fine grass. The young are completely hidden when left by the mother. April 16, 1920, I found a nest containing five young in a stubblefield at Portage Lake. The young were well covered with hair, but the eyes were not open. April 20, 1920, I found another nest containing young on the lawn of an unoccupied house near the shore of Portage Lake. The number of young was not determined. May 5 the young were gone and the nest was deserted. May 16, 1920, L. R. Dice saw four young cottontails with their eyes open in the possession of a boy. They were taken from a nest near Ann Arbor. About May 10, some years ago, I saw a cottontail jump into and swim across Mill Creek in this county. The animal was not pursued nor driven in any way into the water. Sometimes when caught alive the cottontail utters a loud, shrill cry. _Bison bison bison._ American Bison.--According to the reports of the early explorers, this large mammal, in the eighteenth century, occupied, or at least visited, the southern border of the state of Michigan. Although we have no record of its occurrence in this county, its remains have been found just over the western border of the county by L. D. Watkins, who in 1835 picked up three skulls near Norvell, Jackson County (Township 4 south, Range 2 east, Section 22). Two of these skulls were sent to Hillsdale College, where one still remains, though the data with it were lost during a fire; the other skull was sent to Albion College, but cannot now be found. At the time these specimens were collected other bones were plentiful on the surface of the ground. _Cervus canadensis canadensis._ Eastern American Elk.--Probably common over most of the Southern Peninsula of Michigan up until the time of the settlements. I have found no record of live elk seen in the county, and the species probably was extinct in the district before 1800. Bones and antlers are common in the marshes and swamps of the county. _Odocoileus virginianus borealis._ Northern White-tailed Deer.--Abundant in the county when the first settlers arrived, and continued common for many years. It quickly learned to adapt itself to civilization, feeding by night where it formerly fed by day. Some early settlers report much damage done to gardens and crops, of which the deer soon learned the location. The last deer known to me in the county was seen in Saline Township in 1875 by William Gordon, who reported it to me at the time. Covert[5] records one seen in the county in 1879. [Footnote 5: Covert, A. B., in History of Washtenaw County, p. 194, 1881.] _Hypothetical List_ The mammals included in this list have been reported as occurring in Washtenaw County, but I can find no specimens with authentic data nor descriptions satisfactory for identification, and consider the records doubtful.