FAMILY 2. COLIMACEA. 
for) 
“I 
HELIX, Linneus. 
Testa globosa, orbicularis, superné convexa aut conoidea, levigata, rard 
striata, epidermide spissimé induta; spira subobtusa, parim ele- 
vata, anfractu ultimo, peripheria convexa, prominentiore, umbi- 
licum plus minusve distinctum formante ; apertura transversa, in- 
tegra, intus interdum dentata, marginibus disjunctis ; labro vel sim- 
plici vel reflexo. 
When we meet with two animals differing, however minutely, in their 
system of organization, presenting to all appearances a marked peculia- 
rity of character not hitherto noticed, we conceive that each of them is in 
itself of sufficient importance to be regarded as the type of a particular 
genus, or, in other words, that each is entitled to hold its particular rank 
in the binominous form of nomenclature. But when a third animal is 
discovered, presenting an assemblage of characters exactly intermediate 
between those of the two previously known, partaking equally of the 
characters of both, the order or classification is disturbed, for the natu- 
ralist is now puzzled as to which of his two genera it should be referred. 
Two opinions then arise amongst authors; the one is to create a new 
genus specially for its reception, the other to unite the three into one ; 
whilst neither can determine which is the artificial arrangement, which 
the natural. 
The Carocolle, the Anostomata, the Pupe, the Clausilie, the Bulimi, 
the Achatine and the Succinee, though admitted by Lamarck, as by De 
Férussac, to present the same system of organization as the Helices, 
have been separated by that author at different times according to their 
varieties of form or structure, upon the following argument :—that as the 
shell is moulded to the form of the animal, not the animal to the shell, 
these several diversities may, in treating of this extensive series of mol- 
lusks, be safely considered of good generic importance. After assigning 
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