HELIX. 367 
Helix sptrorbts. 
Conchologists, with much probability, have decided that this 
shell was identical with the Planorbis spirorbis of Miiller (Rossm. 
Icon. L. und 8. Conch. f. 63). The paucity of European Pla- 
norbes, and no one can doubt from the description that it be- 
longed to that genus, the recognition of a fair proportion of 
them as Linnean Helices,—thus leaving but few for comparison, 
—together with the specification of the number of volutions, 
has caused the determination of this unillustrated species to 
prove easier than could have been expected. Our author did 
not possess this shell. 
Helix contorta, 
In confirmation of the received opinion, a specimen (Rossm. 
Icon. L. 8S. Conch. f. 117) of the Planorbis contortus of Drapar- 
naud is present in the Linnean collection, where I find no other 
shells which correspond more exactly with the description. 
In the manuscript of the younger Linné a reference to “ Pet. 
Gaz. t. 92, f.8” has been added. That figure, although rude, 
has been also quoted by Dillwyn, Lamarck, &c., for this 
Planorbis. 
Helix corwtt<artetis. 
The determination of this species has been effected without 
difficulty, owing to the accordance of the three synonyms with 
the diagnosis. Its identity with the Ampullaria cornu-arietis 
(Sow. Gen. Shells, Amp. f. 3) has been established by general 
consent. The bands are usually more numerous than is speci- 
fied in the ‘Systema ;’ but in that respect the species appears 
somewhat variable. I may mention the attached locality, 
“Europe”! as confirmatory of my assertion, that no depen- 
dence can usually be reposed in the Linnean habitats: conse- 
quently, when estimating the value of conflicting testimonies, 
