HELIX. 387 
of the ‘Systema,’ where the number of the coils was not 
specified, five whorls are consequently assigned to it by imph- 
cation. 
Nilsson, with much doubt, has surmised the identity of 
limosa with the Limneus truncatulus, but, although his sugges- 
tion is not devoid of plausibility, that shell does not correspond 
with strictness to either the “apertura ovata” of the ‘Systema’ 
or to the “ Habitat in fluviis” of the ‘Fauna.’ The difference 
of habitat in the two works, for “ Habitat in Europe paludibus” 
is asserted of it in the former, argues a confusion of species. 
Perhaps, upon the whole, the hypothesis most likely to be 
correct is that which regards the river-dwelling snail of the 
‘Fauna’ as a narrow form of the ZL. pereger (a shell so abun- 
dant that it must have been seen by Linnzus); nevertheless, 
being composed of four volutions only, it does not adequately 
coincide with the description. It appears to me, then, that the 
Helix limosa was too imperfectly defined for positive deter- 
mination. 
Helix tentaculata. 
This shell is not marked as being in the possession of 
Linneus, but was clearly defined in the tenth edition of the 
‘Systema,’ by references to the ‘ Fauna Suecica’ and to Lister’s 
‘Animalium Anglie,’ both which works clearly indicate the 
Cyclostoma impurum of Draparnaud (Moll. France, pl. 1, f. 20, 
the Bithinia tentaculata of modern writers) as the species 
intended. The allusion to its operculum in the ‘ Fauna’ and 
the comparison of it to vivipara in the same publication, com- 
bined with our knowledge of the fewness of the operculated 
fluviatile shells indigenous to Sweden, would alone have sufficed 
to identify it; but this comparison is not at first obvious, since, 
owing to the transposition of species in the second edition of 
the ‘Fauna,’ the preceding shell to which it is likened appears, 
from the text being unaltered, to be limosa, instead of vivipara, 
which it follows in the arrangement of the first edition. This 
change of order, without corresponding change of language, is 
unfortunately not unprecedented in the ‘Fauna Suecica.’ I 
may instance, as more particularly striking from its incon- 
