56 ox THE PBOBOSCIDEAN FOSSILS OF THE PLEISTOCENE DEPOSITS. 



Associated Fossils. 



From what is kiio\\ii concerning the age of the latest glacial 

 drift, and from the fact that many of the remains have been found 

 in alluvium which is later than this drift, there seems to be srood 

 reason to" believe that elephants and mastodons have inhabited 

 thesestates within the time of the last five thousand years, or per- 

 haps still later. The association of their remains with those of 

 other animals not yet extinct in this part of the world likewise 

 indicates that they hare but recently been exterminated. These 

 associated fossils are of various kinds. In Rock Island, the loess 

 which contained elephant bones also contained fragments of conif- 

 erous wood, and at Davenport, m Iowa, the peaty loess, from 

 which tusks and other bones were taken, has a seam of diatoma- 

 ceous earth, in which no less than thirtj'-three now living species of 

 diatonis have been identified.* Only a short distance from this 

 locality, the same horizon carries the usual land snails, such as 

 Helicina, Succinea, Pyramidula, Bifidaria, Limniea, and others 

 which are characteristic of the loess. IiijSangamon county, in Illi- 

 nois, the mastodon-bearing alluvium contained such common pond 

 snails as Planorbis, Cyclas, and Physa, and at Fairmont, in Ver- 

 milion county, where mastodon remains were found in what ap- 

 pears to be a waterlaid clay, this contained Limntea, Physa, Pla- 

 norbis, and Spha-rium, all typical jiiond mollusks of to-day. 



The mammals which are mentioned as found in immediate as- 

 sociation with the mastodon, are the American buffalo, or the 

 bison, which is reported from three localities, the wolf, the peccary, 

 the deer, and the elk, each of which is reported only once. In the 

 country around Chester and Alton, in Illinois, where Professor 

 Wm. McAdams made extensi^'e observations on the fossils of the 

 loess many years ago, he is reported as having found in this de- 

 posit Mastodon, Megalonyx. Bosprimigenius. Castoroides, ohio- 

 ensis, and mau\- small rodents. The latter occur in the so-called 



* See Iowa Geological Sur\ey. Vol. IX, p. 356. 



