SUMMARY OF THE LIFE OF THE PLEISTOCENE 371 



A less number are from cave deposits thot to be preglacial, while a few are from 

 other interglacial and postglacial deposits. Nearly all of the insects are beetles 

 (Coleoptera) and the majority of the species belong to the families Carabidae 

 and Staphylinidae, the first represented by 51 species and the last by 20 species. 

 Other orders of insects are but meagerly represented, only one, Phryganea, be- 

 ing certainly identified. The insect fauna of the Pleistocene will probably be 

 very largely increased in number of species when the interglacial peat deposits 

 are more carefully examined. 



III. VERTEBRATA 



The vertebrates, like the insects, are notable for the large number of extinct 

 species represented. In this group of animals, whole families are extinct, notably 

 Megatheriidae, Equidae, Camelidae, Elephantidae, and Castoroididae. Among 

 the other families, upwards of half the species are now extinct. The number of 

 species which survived the glacial episodes and became extinct during postglacial 

 (Wabash) time is notable. These are: 



^ Megatherium jcjfcrsoni Boothcrium sargcnti 



Platygonits comprcssus Symbos cavifrons 



Mylohyiis nasutus Mammut americanum 



Ccroalccs scotti Elephas primigenius 



Cervakes borealis Elephas columbi 



\ ] Bison laiifrons Casloroides ohiocnsis 



Conditions for these animals, as well as for the insects, must have changed 

 radically before the recent or human period. The strong South American 

 element in the vertebrate fauna is to be especially noted — Megalonyx, Platy- 

 gonus, Mylohyiis — and also that some of these (as Platygonus) extended in 

 postglacial time as far north as New York, Indiana, and Michigan. A northern 

 element is also present in the vertebrate fauna, consisting of the mastodon, 

 northern elephant (mammoth), bison, bear, reindeer, and musk-ox. The 

 horse, so abundant in the Pliocene Period, becomes scarcer and scarcer, and 

 the last authentic records seem to be in the Sangamon interglacial interval. 

 The camels became extinct very early in the Glacial Period. The remains 

 of the Cervidae, Bovidae, Elephantidae, and Canidae occur thruout the 

 different interglacial intervals, indicating that during these intervals a varied 

 mammalian fauna existed. 



Cope, Osborn and other paleontogologists have divided the Pleistocene 

 mammals into faunal zones thereby dividing Pleistocene Time into periods 

 corresponding to these faunas. Cope 4 divided the mammals into two faunas, 

 one the Megalonyx fauna, the other the Equus fauna, the former inhabiting 

 the region east of the Great Plains and the latter the western and southwestern 



* Amer. Nat., XXIV, p. 593. 



