382 SPECIES OF THE SYSTEMA. 
unlike the description of it in the ‘Systema,’ but the pillar is 
so decidedly imperforated as not to afford grounds for the use 
of the term “ subperforata”’ in the diagnosis, even when subse- 
quently modified into “umbilicus adeo obsolete perforatus, ut 
vix constet utrum vere perforatus dicendus.” With such ad- 
verse particulars, even had that common shell been present 
(which it is not) in the Linnean cabinet, the identification, un- 
supported by correspondence with the cited figure, must, at 
least, have been esteemed conjectural. Pennant, with some 
doubt, has attached the name octona to the Limneus glaber ; 
the shape of the aperture in that shell, however, is not roundish 
but elongated ovate. By far the most reasonable surmise is 
that of Nilsson, who, in his ‘ Historia Molluscorum Suecie,’ 
has described a Paludina octona, which not only fairly agrees 
with the Linnean description, but corresponds also with the 
assigned locality (“ Habitat in Sueciz subpaludosis’’), and ap- 
proaches more nearly to the limited size attributed to the 
species than the West Indian Bulimus. The authority of that 
writer, too, is of great weight upon the Swedish shells; and 
although I have recorded my opinion of the little dependence 
to be placed upon the correctness of the Linnean localities, 
yet this stricture Was not intended to apply to the indigenous 
species, which our author had both studied more peculiarly, 
and separately treated of in the ‘Fauna Suecica.’ It is pro- 
bable that when he published that work he had not observed 
this little shell, since no notice was there taken of it; and the 
publication of the twelfth edition of the ‘Systema,’ wherein it 
first appeared, was posterior by some years to the date of the 
last edition of the ‘ Fauna.’ 
Menke, in the ‘ Zeitschrift fiir Malakozoologie’ for 1845, 
agrees with the conclusion of Nilsson, but regards the present 
as merely a produced form of the preceding species. 
Helix pella, 
As was generally the case with the smaller species of 
Linneus, the older writers have added nothing to our know- 
ledge of the present shell. Menke, in the ‘ Zeitschrift fiir 
