Editorial Comment. 185 
EDITORIAL COMMENT. 
The Columbian Exposition. 
Notes on some Mesozoic and Tertiary Exhibits. 
The United States Geological Survey. 
The Survey presented in the Government building a synop- 
tic exhibit under the caption of "Systematic Collection of 
Rocks and Fossils." This included a series of selected and 
prominent types of Mesozoic and Cenozoic rocks and fossils 
arranged primarily according to stratigraphic and geographic 
divisions, and subordinately, as to fossils, according to zoolog- 
ical and botanical relationships. 
The maps showing the geographic distribution of the 
Eocene and Neocene and of the Cretaceous systems within 
the United States, exhibited in connection with the corres- 
ponding collections, were for their general pretensions reas- 
onably accurate, as to those parts at least with which the 
writer is most familiar, one of the least satisfactory parts of 
the Cretaceous map being, perhaps, Kansas south of the Ar- 
kansas river. But no such map should be expected to present 
detailed accuracy. 
The Tertiary collections were divided into Eocene and 
Neocene, and for the most part, without further attempt to 
specify the horizon, except as it might be implied in the 
geographical locality named on the label. The chief Eocene 
localities from which specimens were exhibited were, for In- 
vertebrata, Jackson, Vicksburg, Caton's blurt', Claiborne, 
Wood's" bluff, etc.; and for leaf impressions, Green river and 
Florissant. The Neocene fossils were given, in the main, 
only States as localities, exceptions being shells from "York- 
town, Va., Lower Neocene" and plants from Cherry creek and 
John Day valley, Oregon, and Coral Hollow, California. 
The Cretaceous collections were primarily divided into Up- 
per and Lower. In the Upper Cretaceous, a small series of 
fossils from the recently redefined Bear River formation con- 
stituted a feature of special interest. It included the follow- 
ing forms : Campeloma macrospira Mk., Pyrgulifera humer 
oSa Mk., Goniobasis cleburnii White, Corbula pyriformis Mk., 
Corbicula durkeei Mk., Unio vetustus Mk., and IT. belliplicatus 
Mk. 
