In this case one can not be certain that the tusk did not belong to one of the elephants. From information accompanying the specimen one can determine little about the exact geological age of the animal. It is probably post-Illinoian.
12. _Rural Township, Rock Island County._—Dr. J. A. Udden (in Netta C. Anderson’s list, p. 18) reported that there is in the collection of Augustana College, Rock Island, a well-preserved tooth of a mastodon, found in 1900, in a creek in the township named, in the southeastern corner of the county. Udden gives the locality as being in section 19, township 16 north, range 1 west.
In the same institution (J. A. Udden, Augustana Coll., Pub. No. V, p. 12) is a part of a proboscidean tusk, referred to the mastodon, which Dr. Udden states was found near Milan, at the base of the loess, in the red oxidized layer of the Illinoian boulder clay. The locality is on the north side of Rock River and on the east side of the Milan road south of Rock Island. The conditions would seem to indicate that the animal had lived about the close of the Illinoian drift stage.
About June 15, 1916, Mr. A. Daxon, of Omaha, Nebraska, sent photographs of two mastodon teeth to the U. S. National Museum for identification. These teeth were found in Bowling Township, Rock Island County, 10 or 12 miles south of Rock Island, but no further information about them has been secured.
Professor J. A. Paarmann, curator of the Davenport, Iowa, Academy of Sciences, has written that he had seen a finely preserved mastodon tooth which had been picked up on the surface of the ground a mile west of Milan. The land around about is swampy. The tooth was in the possession of Edward Herbert, Rock Island, Illinois, but the present writer has not been able to get any information from him.
13. _Sterling, Whiteside County._—In the U. S. National Museum (No. 4222) is a mastodon molar, recorded as found near the town named. It was transmitted through the U. S. Geological Survey and credited to T. A. Schroder. It is said to have been found with other teeth and parts of the skeleton, so that there is little probability that the skeleton was disturbed after its original interment. It is to be regretted that so little information was allowed to come with the specimen.