82 THE NAUTILUS. 
of an illustrated monograph on the mollusks of Cook and DuPage 
Counties and adjacent portions of Will Co., Illinois, and Lake Co., 
Indiana. Mr. Baker prefaces his account by a useful general con- 
sideration of the structure of mollusks, their preparation for study, 
collection, ete., with full notes on the general character of the Chi- 
cago fauna, localities where the various forms occur, and other in- 
formation and statistics which will prove of great use both to 
subsequent naturalists in that locality, and to those who may have 
occasion to compare the fauna with that of some other district. 
In the treatment of the species, full descriptions of each at various 
stages of growth are given, with the synonymy, distribution, judi- 
cious comparisons with allied forms, and more or less extended ac- 
count of the soft parts. 
In the generic arrangement, the assistance of Mr. C. T. Simpson 
has been secured ; and the old genera Unio and Margaritana have 
been dismembered, and their species distributed among Alasmodonta, 
Strophitus, Unio, Anodontoides (a new genus for Anodonta ferussa- 
ciana and subcylindracea), Quadrula, Obliquaria, Plagiola and 
Lampsilis, the latter with subgenera Metaptera, Euryma and Corun- 
culina (new section for U. parvus). Those familiar with Mr. Simp- 
son’s studies of this family will probaby agree with us that these 
genera are well founded, and their recognition is a distinct advance 
in our knowledge of the group. Most of them were originally 
founded by Rafinesque ; but their limitation and definition is essen- 
tially Mr. Simpson’s own work. 
The plates are excellent half tone reproductions of photographs. 
Some of them are among the best figures of Uniones we have seen ; 
and while a few do not show the details of the teeth as well as could 
be desired, and we would prefer them to be printed in a different 
color, still there is little to criticize. They are a distinct success. 
Conchologists throughout the middle west, as well as others inter- 
ested in the shells of that region, will find Mr. Baker’s book of great 
service. While there are a few slips, such as the statement on p. 12 
that the mollusca are “ of quite recent date geologically,” and on p. 
11 that in one group (Gastropoda) the mouth is provided with a 
radula, where the author probably meant that a radula is present 
in all but one of the groups (Peleeypoda), still such oversights are 
few. 
We heartily congratulate the Chicago Academy of Sciences upon 
the appearance of the work, and their success in placing before its 
