PALEONTOLOGY: C SCHUCHERT 
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from the rivers to the sea in the mid-Paleozoic, though their remote 
ancestors may have ascended from it" (404). Finally, that the lands 
were clothed with vegetation even in Proterozoic time and that there- 
fore there was an abundance of food in the rivers is attested in part by 
the great quantity of carbonaceous material in the strata of this time, 
plus the complete disintegration of the crystalline rocks as is shown 
by the fine aluminous muds, the clean sandstones, the great amounts 
of limestone, and the locaHzed beds of iron-ore. Although arkoses 
are present (broken up and undecomposed granites), their mass is in- 
significant in comparison with the quantity of the other sedimentaries. 
Early in 1916 Prof. Joseph Barrell also considered the probable 
first habitat of fishes, but from the standpoint of their occurrence as 
fossils in the rocks, in papers entitled Dominantly fluviatile origin under 
seasonal rainfall of the Old Red Sandstone and Influence of Silurian-Devo- 
nian climates on the rise of air-breathing vertebrates.^ He agrees with 
Chamberlin and concludes that it is probable ''that fishes arose in land 
waters" and ''as such they constituted primarily a river fauna." The 
lung-fishes arose under semiarid climates and seasonal waters. "The 
exposure of the tidal zone alternately to water and to air had, then, 
nothing to do with the origin of lungs." "The evidence is regarded as 
strong that the air-bladder was originally developed as a supplemental 
breathing organ, although in modern fishes it has been mostly diverted 
to other uses. Among certain Devonian fishes, Hving under more and 
more strenuous climatic conditions of seasonal dryness, the use of the 
air-bladder for respiration became essential, and with the diminishing 
availability of the waters of certain regions the gills in those species 
which survived this crisis in evolution became correspondingly atrophied. 
The amphibians thus arose under the compulsion of seasonal dryness." 
Finally, "Climatic oscillation is a major ulterior factor in evolution" 
(388-391). 
Later in 1916 appeared a suggestive memoir entitled The habitat of 
the Eurypterida, by Dr. Marjorie O'Connell,^ which has stimulated the 
writing of these remarks. This work seeks to point out the actual habi- 
tat of eurypterids during the Paleozoic, as derived from a study of their 
entombment in all places Paleozoic, but chiefly in America and Europe. 
It is replete with paleontologic information, and all of the more impor- 
tant occurrences of these animals and their immediate associates are 
described in as much detail as the author was able to glean, in the main 
from the widely scattered literature, though she is also familiar with 
the actual field relations in the state of New York. There are in all 
the world about 130 described species in 14 genera, with the acme of 
