Ve HISTORICAL SKETCH OF PREVIOUS MONOGRAPHS. 
The fresh-water Pulmonata have been written upon to a greater 
extent than almost any other group of mollusks, excepting perhaps, the 
land snails. Scarcely a paper has been published on inland mollusks 
that did not mention some member of the group, hence the literature 
is extensive. Of illustrated monographs and other papers of a mono- 
graphic character dealing with American Lymneas, upwards of six- 
teen have been published that are especially notable. These may be 
summarized as follows: 
I. 1832-34. THomas Say. In his American Conchology, Say, 
the father of American Conchology, enumerates and figures 6 species 
of the genus. The Journal of the Academy of Natural Science of 
Philadelphia also contains descriptions of many species, published 
between the years 1817 and 1825. The article “Conchology” in the 
American edition of Nicholson’s Encyclopedia of Arts and Sciences, 
contains 2 species of Lymnza. 
II. 1841. Aucustus A. GouLp. In the Invertebrata of Massa- 
chusetts, Dr. Gould lists and figures for the most part 7 species and 
1 variety of Lymnza from New England. This report was reprinted 
in 1870 under the editorship of Mr. W. G. Binney. 
Ill. 1842. S. S. Harpeman. This is one of the best of the 
monographs of Lymnza, the figures being superb, exceeding in this 
respect those of any other monograph. 24 species are described and 
figured. An attempt is here made to divide the American Lymnzas 
into subgeneric groups, five of which are recognized, two being de- 
scribed as new. 
IV. 1848. James E. DeKay. In the Zoology of New York 23 
species of Lymnza are mentioned, 15 of which are figured. 
V. 1858. W.G. Binney. In Binney’s edition of the complete 
writings of Thomas Say on the Conchology of the United States 16 
species are described, many of them being figured. 
VI. 1862 anp 1886. H.C. Kuster and S. Ciessin. H.C. Kiis- 
ter began a monograph of Lymnza in the Conchylien Cabinet of Mar- 
tini and Chemnitz in 1862 which was completed by S. Clessin in 1886. 
40 American species are described and figured in the two parts of 
this monograph. 
