LYMNZEIDA OF NORTH AMERICA. 313 
to be confined to any particular locality, but is found in any consider- 
able lot of shells from any locality. (See the figures on the plates. ) 
It is evident from a study of the figures of palustris in European 
works (Forbes and Hanley, Sowerby, Martini and Chemnitz, etc.) 
that the large, rather corpulent form is to be considered as typical. 
This form is absolutely identical with American specimens, series from 
both continents being indistinguishable when mixed. There are, how- 
ever, several varieties or races which seem recognizable. Very distinct 
variations are frequently seen in shells from different parts of the 
same body of ‘water, as notably illustrated by the palustris in Owasco 
Lake, N. Y., where specimens from the west shore are very large and 
thin (pl. XX XIII, figs. 2-7) while those from the north end are smaller 
and very solid, in some individuals recalling both Galba catascopium 
and Galba palustris desidiosa (Pl. XXXII, figs. 8-10). 
A study of the types of Lea’s Lymmnzeas in the Smithsonian Insti- 
tution conclusively proves that nuttalliana (pl. XXXII, figs. 22-23) 
and haydeni (pl. XXXIII, fig. 25) are absolute synonyms of palus- 
tris, haydeni being a slight modification of the nuttalliana form, The 
characteristics of a corpulent shell or a strongly plicate columella are 
of no consequence whatever when a series is examined, such as is 
shown on plate XX VI, where figs. 20 and 17 seem very distinct when 
placed side by side, but are seen to be easily and gradually connected 
with each other in a large series. (Compare also fig. 21 with fig. 26.) 
These mutations are very interesting, but are not of taxonomic im- 
portance, being simply individual variations. Lymnea expansa Hald. 
is a form in which the outer lip is expanded; the same is true of suf- 
flatus Calkins. Plebeia Gould, a nude name, is an absolute synonym 
of palustris. Limneus sordidus Kister, is a synonym of palustris, 
judging by Von Martens’ references to Haldeman, plate 6, figure 1. 
The locality “Central America” is an error as no member of the palus- 
tris group (except attenuata) is found south of the Rio Grande. It 
is probably a case of mixing labels. Specimens in Dunker’s collec- 
tion, now in Berlin, are said by Von Martens to be like Haldeman’s 
figure 5 on plate 7. These are marked “Central America.” 
Unlike the Lymnzas previously considered (excepting caperata) 
palustris forms several distinct ribs or rest varices in its shell, as many 
as four being distinctly seen in some specimens, although three seem 
to be the normal number. In the majority of specimens one varix is 
formed on the third whorl, one on the fifth whorl and one on the 
margin of the aperture. Whether these varices are formed yearly or 
simply mark periods of hibernation when the animal is buried in the 
