Dr. E. von Martens on the Species of Amphipeplea. 211 
species, inhabiting the Lake De Joux, in western Switzerland, 
has indeed the general outlines of shell similar to those of Am- 
phipeplea ; but, judging from a specimen in the Albersian collec- 
tion presented by Carpenter himself, who sent the specimens to 
Rossmassler, the author of the name, I can state that neither is 
the outer surface of the shell so glossy as in Amphipeplea, but 
rather dull, nor is the parietal lamina in any way extended beyond 
the limit common to the true Limnei. In both respects it 
closely resembles the common JL. auricularius and L. ovatus, and 
may safely be considered one of the numerous varieties compre- 
hended under these two names. 
Some British authors, and among them Adams (Gen. Moll. i. 
p- 256), admit into the genus Amphipeplea a shell from an Alpine 
lake near Killarney, Limneus (or A.) involutus, Harvey. I have at 
present no opportunity of examining the shell ; but the figure of 
the living animal given in Gray’s figures (Moll. An. pl. 301. 
fig. 3) is that of a Lamneus, not that of an Amphipeplea. Jeffreys 
(British Conchology, i. p. 104), however, states the following :— 
“Dr. Perceval Wright informs me that the greater part of the 
shell in this species (Limnea involuta) is covered by the mantle, 
as in LZ. glutinosa. The form and substance of the shell are also 
similar in both of these species.” But the same author, in the 
same book, on the preceding pages, terms the shell of L. gluti-— 
nosa (true Amphipeplea) “excessively thin, highly polished, 
transparent,” that of the questionable LZ. involuta only “ rather 
glossy, semitransparent,” just as he terms that of L. auricularia 
“thin, glossy, semitransparent ;” so that, judging from his 
words, the substance of the shell of L. involuta is nearer to that 
of L. auricularia than L. glutinosa,—t. e. that of a true Limneus, 
not of an Amphipeplea. Most specimens of Limneus auricularius, 
ovatus, and pereger exhibit on the outside of their shell some 
thin incrustation of muddy or vegetable matter, which never 
oceurs in Amphipeplea. I think that a careful examination of 
the shell alone would enable us to arrive at a more satisfactory 
conclusion as to the accordance either with Limneus or with 
Amphipeplea. Judging from the published descriptions and 
fizures of the shell, I think that Forbes and Hanley are right-in 
suspecting it to be some variation of a more ordinary Limneus ; 
indeed it seems to have the same relations to the smaller varie- 
ties of Limneus ovatus (L. vulgaris, Pfr.) as L. Monnardi and L. 
tumidus, Held (= amplus, Hartm.), to auricularius, L. roseo- 
labiatus to L. pereger, L. lacustris to L. stagnalis—that is, to be 
a more involuted lacustrine variety of it. The term “ znvolutus” 
- itself I imagine to have been applied to it on account of the 
involution of the whorls, and by no means to indicate an enve- 
lopment of the shell by any soft part. 
14* 
