1894.] Recent Literature. 255 
“In summing up this subject, it may be affirmed that when the stri- 
ation and transfer of materials have obviously been from N. E. to S. 
W., in the direction of the Arctic current, and more especially when 
marine remains occur in the drift, we may infer that floating ice and 
marine currents have been the efficient agents. Where the stria- 
tion has a local character, depending upon existing mountains and 
valleys, we may infer the action of land ice. For many minor effects 
of striation, and of heaping up of moraine-like ridges, we may refer to 
the presence of lake or coast ice as the land was rising or subsiding.” 
Again, “Sea glaciation is always accompanied with much smoothing 
and polishing, and on very hard rocks the striation is comparatively 
imperfect, while it is not quite uniform in direction and often presents 
two sets of striae. The action of true land glaciers, especially when 
moving down considerable slopes, produces deep grooves, as well as 
striae, on vertical as well as on horizontal surfaces, and is nfore fixed 
and uniform.” 
The summary of fossils given in Chapter VI, comprises 240 species, of 
which 33 are plants; the rest are distributed as follows: Protozoa, 21 ; 
Echinodermata, 7; Mollusca, 142; Vermes and Arthropoda, 30; Ver- 
tebrata, 7. From both flora and fauna the author infers an ameliora- 
tion of the climate, resulting, in his estimation, from the gradual eleva. 
tion of the land which threw the Arctic currents from its surface, ex- 
posed a larger area to the direct action of solar heat, and probably 
determined the flow of marine currents so that the heavy northern ice 
was led out into the Atlantic instead of being drifted southwest over 
the lower levels of the continent. 
The leading thoughts in this collection of papers is the relative value 
of land ice and water-borne ice as causes of geological change during 
the Plistocene period. These two agents, together with the complex ele- 
vations and depressions of the continent as shown by the deposits and 
their fossil contents account for the effects observed. 
This paper is an important one, and will probably correct the 
extravagancies into which the past glacialists have faller. 
The Mollusc-Fauna of the Galapagos Islands.’—The mol- 
luscan forms collected by Professor Leslie A. Lee and his assistants, on 
the voyage of the U. S. Fish Commission Steamer Albatross, from 
* Scientific Results of Explorations by the U. S. Fish Commission Steamer Albatross. 
No. XXV. Report on the Mollusk-fauna of ha Galapagos Islands, with Descriptions 
of New Species. By Robert E. C. Stearns, Ph. D. Adjunct Curator of the D 
ment of Mollusks. Proc. U. S. Nat. Mus., a pas, (1893) pp. 353-450, with plate 
d map. 
