250 The American Geologist. October, 1893 
form a horse-shoe shape in cross-section ;is is said to be the 
case in the English species. 
Towa City, /<>.. Sept., 1898. 
EXPLANATION OF PLATE XI. 
Bennettites dacotensis Macbride. 
Pig. 1. Lateral view of a large, perfect individual, showing lateral 
buds and other characteristics. Leaf bases have rotted out, leaving 
lozenge-shaped pits. 
Fig. 2. Portion of surface of another individual a little less than one- 
half natural size, showing transverse sections of leaf -bases and distri- 
bution of fibro-vascular bundles. 
EDITORIAL COMMENT. 
The Columbian Exposition. 
Geological Map*. 
The display of geological maps, charts, sections, etc., in 
the Exposition is large. As in other departments, some 
countries are fully represented, others are " conspicuous bj r 
absence." 
The following notes on the geological maps exhibited are 
merely an attempt to outline some of the chief features of 
this part of the exhibition. They make no pretense to com- 
pleteness, partly in consequence of the large number and va- 
riety of maps, partly because of the great difficulty of obtain- 
ing full information, and largely on account of the way in 
which the material is scattered over the 500 acres of ground 
enclosed within the walls. These reasons, and especially the 
last, made the task of completing an exhaustive list hopeless 
from the first. 
It would be invidious to select any one country or any two 
or three countries for prominent notice, because conditions, 
experience and age are factors of immense importance in the 
problem. No regard therefore must be attached to the order 
in which these exhibits are here mentioned. This is chiefly de- 
pendent on the order in which they were examined. 
Japan has an excellent geological display. The survey of 
the empire is about half finished, on a scale of one-millionth 
