20 PROCEEDINGS OP THE SCIENTIFIC ASSOCIATION. 
In the genus Amphibulima the animal is incapable of re- 
traction into its shell, and the latter is entirely, or almost 
entirely covered by the mantle. These characters do 
not obtain in Succinea. Distinctions of less importance 
than these are considered sufficient for the establishment 
of undoubted genera ; and a glance at the shells will show 
that they cannot be ranked with Succinea . 
I have been favored by Governor Rawson, C.B., with a 
specimen of Omalonyx unguis Fer. from Guadelupe. That 
shell is faithfully represented in Woodward’s Manual of 
the Molluska (pi. xii., f. 24), and it scarcely differs from, 
the Trinidad form. I do not know the soft parts of the 
Guadelupe mollusk : but it appears to me that a question 
here arises — the soft parts of 0. unguis , as figured by 
d’Orbignv, are different from the Trinidad mollusk. 
D’Orbigny’s animal was from South America, but Ferus- 
sac’s type appears to have been the Guadelupe shell It 
may then possibly turn out that d’Orbigny’s species is not 
the same as Eerussac’s. Should the latter prove to be 
identical with the Trinidad shell, the name given by me 
must be abandoned, and a new appellation given to 
d’Orbigny’s ; but it is not improbable that all three are 
really distinct ; for in a group like Omalonyx , where the 
shells are rather deficient in very marked characters, it 
may easily be that the specific differences are not so dis- 
tinctly impressed upon the shell as upon the soft parts. 
When recording my discovery of Amphibulima palula in 
Dominica, I gave no description of the animal, believing 
it already well-known to naturalists. At present I can 
only say that in general features it bears a resemblance to 
Omalonyx unguis as figured by d’Orbigny (Vo y. Amer, 
