256 The American Naturalist. [Mareh, | 
Chesapeake Bay by the way of the Strait of Magellan to San Fran- 
cisco in 1887-88, is the basis of this paper which is, as will be seen in 
the foot-note, a report on the Galapagos material belonging to this 
division of the animal kingdom. As the author states in the text, it 
“ refers, so far as the marine molluscs are concerned, with a few excep- 
tions, to the littoral and shallow-water species only.” The deep sea 
material remains to be investigated and reported on hereafter, though 
a few species described by Dall are included in the list, in the later 
part of the report. , 
The geographical and physical characteristics of the islands, their 
climatology and floral aspect, the distances and depths of the water 
between them, their origin, and the views of Darwin, Hooker, Wall- 
ace, Agassiz, Baur, ete., hereon are briefly presented. The origin of 
the fauna and the flora is discussed, and in this connection the distri- 
bution of terrestrial and marine forms, etc., by oceanic currents, drift | 
lodgement,.freshets, and the agency of rivers, and the aerial distribu- 
tion of animal and plant life, as well as the generative capacity i 
vitality of land snails, their ability to exist a long time without food 
of which numerous instances are given, and the tenacity of life Bo 
many species that have been observed, are all referred to and trea 
at considerable length. 
The author favors the volcanic theory of the region of these islands 88 
held by the majority of scientific writers, rather than that of Dr. Baur 
and Milne-Edwards, who regard the Galapagos as « Continental Islands | 
originated through subsidence,” a conclusion based principally T 
biological evidence, ete.. as exhibited in their peculiar fauna and 
The number of mollusean species and varieties obtained es re 
Albatross collectors was 120, of, these 7 species and 9 varieties a 
terrestrial forms. Four new species are described, and one of these 
a land shell, Bulimulus (Pleuropyrgus) habelii; the others are © 
ium lesliei, Nitidella incerta, and Tectarius galapagoensis. 
As a part of the report, the late Dr. Philip Carpenter’ 8 
Galapagos species contained in Reeve’s Monograph’s 38 a 
Albers’ list of Galapagos Bulimi; the Petrel-Cookson shells, 885 5 y 
mined by E. A. Smith of the British Museum; Wimmers S 
Habel’s collection; Ancey’s species, and Reibisch’s list of pe 
lected by Dr. Theodor Wolf, State Geologist of Ecuador; Dr. 
Jones’ Chatham Island shells, Dall’s recently described G9 ™ * 
a a at ; f the Albatro® 
pecies, including a few deep water forms, a part 0 Se 
dredgings, and a few land species collected by Dr. Baur. 
