136 THE CHICAGO ACADEMY OF SCIENCES. 
shells are thin and brittle, with a more or less flaring aperture, a gyrate 
and imperforate axis and a simple peristome. 
The genus Lymnea has been credited to several authors (Bru- 
guiere, Draparnaud, Montfort, etc.), but is clearly due to Lamarck, 
who correctly diagnosed the genus in 1799. Bruguiere has frequently 
been quoted as its author, although the reference in the Encyclopédie 
Méthodique is clearly referable to Lamarck, Bruguiere, as Dr. Dall 
remarks, “having nothing to do with it.” The name Lymnea has been 
spelled in six different ways—Lymnea, Lymnea, Lymneus, Limnea, 
Limnea and Limneus. Etymologically the name should be spelled 
Limnea, but there seems to be no valid reason why Lamarck’s original 
spelling should not be used. If the law of priority is to be adhered 
to strictly, there is then no other course. Some of the early American 
conchologists spelled the name correctly, but during the last forty or 
fifty years the name has been almost universally spelled Limnza, Dr. 
Pilsbry (Nautilus, XVIII, p. 63, 1906) was the first modern zoologist 
to revise the original spelling, which has been generally accepted among 
American conchologists. The name Limnza was used by Poli in 1791 
for a heterogeneous assemblage of pelecypods, but his curious quadri- 
nomal system does not enter into systematic nomenclature. 
Lymnea stagnalis (Linné). Plate XIX, figures 1-3. 
Helix stagnalis LinnE, Syst. Nat., Ed. X, p. 774, 1758; Ed. XII, p. 
1249, 1767.—Baker, Science, n. s., ¥ XVII, p. 943, 1908. 
Lymnea stagnalis LAMARCK, Prodr., p. 75, 1799. 
SHELL: Elongated (or oval), ventricose at the anterior end, thin; 
periostracum yellowish-horn to brownish-black ; surface shining, growth 
lines numerous, crowded, more or less elevated, crossed by numerous 
fine, impressed spiral lines; apex smooth, brownish horn color ; whorls 
six to seven, rapidly increasing, all but the last two rather flat sided; 
last whorl very large, considerably dilated and inflated, inclining to 
form a shoulder; spire long, pointed, acute, occupying about half the 
length of the entire shell; sutures distinct, sometimes impressed ; aper- 
ture large, broadly ovate, dilated, particularly at the upper part; 
peristome thin, acute, anterior part rounded; parietal wall with a rather 
wide, spreading callus which is closely appressed to the body and either 
completely closes the umbilicus or leaves a very small chink; pillar 
of the columella gyrate, usually forming a more or less heavy, oblique, 
ascending plait. 
Aperture 
Length. Breadth. length. Breadth. 
49.00 24.00 27.00 14.00 mill. Baden, Germany. 
1.00 23.00. © 27-00” S42700° * ¢ i 
