196 The Ametican Geologist. Marcii, iwki 
"Wood River mining' district, Idaho," Waldemar Lindgren; 
"Cretaceous fossils collected b)' J.B. Hatcher in Patagonia," 
T. W. Stanton; "A new meteorite," G. P. Merrill. On Feb. 
28th the program included a paper on "The Gulf of Califor- 
nia as an evidence of marine erosion," by VV J McGee, and 
a discussion on "Conditions of formation of conglomerates 
and criteria for distinguishing between lacustrine and fluvia- 
tile beds." 
The Geographic Society of Chicago has recently is- 
sued its Bulletin No. i, entitled "The geography of Chicago 
and its environs," b}- Rollin U. Salisbury and William C 
Alden. This is a pamphlet of 64 pages; it ma)- be obtained 
from Mr. C. E. Peet, Lewis Institute, corner of Madison and 
Robley streets, Chicago; the price is 35 cents. The society 
announces that its membership is open to all persons inter- 
ested in the acquisition and diffussion of geographic know- 
ledge. Lectures are announced for the winter and spring 
of 1900 as follows: Jan. 13, "The bad lands of Dakota" b)' 
Prof. O. C. Farrington; Jan. 27, "The relations of geograph- 
ic distribution to the origin of species," b\- Prof. C B. Dav- 
enport; Feb. 17, "Wyandotte cave," b\' Mr. Wallace W. At- 
wood; March 17, "Some connection between the histor)- 
and geography of the New England plateaus," by Prof. F. 
J. Turner. 
A SECOND LETTER FROM Mr. Agassiz, published in 
Science for Jan. 19th, gives the result of the Albatross cruise 
up to Nov. 9, 1899. Some of the work entailed a thorough 
revision of the Challenger observations. Attempts to mea- 
sure the rate of growth of corals at point Venus, Tahiti, fail- 
ed, partly owing to the scarcit}' of living forms. The western 
islands of the Paumotus are probably situated on a large pla- 
teau, from which spurs are given off. There is no evidence 
of subsidence; on the contrary a broad elevation has taken 
place, sufficient to protrude Tertiar}- coral limestone,, which 
forms the base of the atolls, above the surface of the sea in 
man}' places. The ledges of this rock have been much de- 
nuded, and the debris scattered about as conglomerate or 
breccia. Thus the ver}' erosion supplies material for build- 
ing up the reef again. The detritus also forms extensive 
bars, and often entireh' separate islands, by transportation 
and cementation. Only one case was seen, of a complete!)- 
inclosed atoll, despite the emphatic statement of Dana and 
others, which may not have been founded upon observation. 
The reefs show a great monotony of species of corals, but 
many millipores are found incrusting the seaward sides, 
where they are so vigorous as often to form the outer edge 
of a secondary barrier reef which is common in the Pau- 
motus. 
