118 THE CHICAGO ACADEMY OF SCIENCES. 
VII. 1865. W. G. Binney. Land and Fresh-Water Shells of 
North America. This is the most complete and pretentious mono- 
graph of American Lymnzeas which has yet been published and has 
been constantly referred to by all workers on this group of snails. 
Its great drawback has been the extreme conservatism with which the 
author treated the species, placing many names in the synonymy of 
other species which, upon recent critical study, have been found to 
be worthy of recognition. 31 species are considered valid by Binney. 
Figures (mostly outline) are given of all the species of American Lym- 
nzeas, which had been described at that time, some 80 in all. 
VIII. 1872. Gro. W. Tryon, Jr. Continuation of Haldeman’s 
Monograph of the Fresh-Water Univalve Mollusca of the United 
States. In this monograph 37 species are recognized, 32 figures being 
given on three plates. An attempt is made to utilize a number of group 
names in a subgeneric sense. While not as conservative as Binney, 
Tryon’s work nevertheless shows that little critical study was given to 
the smaller species of the genus. 
IX. 1872. G. B. Sowersy in Reeves’ Conchologica Iconica, In 
this monograph, which is fairly well illustrated, 40 species of Ameri- 
can Lymneas are recognized and figured. 
X. 1880. Fiscuer, PAut and Crosse, H. In the Mission Scien- 
tifique au Mexique et dans l’Amerique Central, these gentlemen de- 
scribe 4 and figure 2 species of southern Lymneeids. 
XI. 1874. W. D. HartMan and Ezra MICHENER, in Concholo- 
gia Cestrica, figure and describe 8 species of Lymnza from the eastern 
part of the United States. 
XII. 1899. Epuarp von Martens. In the Biologia Centrali 
Americana, Mollusca, this author describes 6 species of Lymneeids 
principally from the Central American region. 
XIII. 1900. R. E. Catt. In his report on the Mollusca of In- 
diana, this author describes and figures 5 species. 
XIV. 1902. F.C. BAKxer. In the Mollusca of the Chicago Area, 
Part II, this author describes and figures 10 species of Lymnzas which 
inhabit northern Illinois. 
XV. 1904. JostrAn Keep. In West American Shells, this 
author describes 9 and figures 4 species of west coast Lymnezas. 
XVI. 1906. W.H. Dati. In the Land and Fresh-Water Mol- 
lusks of Alaska, this author figures 26 species of Lymmezeas as occur- 
ring in the northern part of the United States and in British America. 
This essay is the first attempt to place the classification of this group 
of fresh-water shells on a modern basis. 
