LITTORINID/E. 339 
forms resulting from the substances on which they are fixed, 
combined with the influencing effects of habitat, food, and 
depth of water. 
I have recently exammed and dissected 500 Anomie of 
all forms, sizes and colours, from different habitats, and in 
the endless variety of colour and markings of this proteiform 
genus I have not discovered a specific character, either as 
regards the anatomy or the external organs of this genus, that 
would justify the creation of a single species. I have now done 
with the Anomie, as the learned editors of the ‘ British Mol- 
lusca’ have recorded these opinions in their interesting work, 
though without any particular concurrence therein. But in 
corroboration of these views I shall adduce some considera- 
tions on another genus, which has largely contributed to the 
increase of pseudo-species; I allude to that portion of the 
genus Littorina designated L. littorea and L. rudis. 
This well-known family, as now constituted, consists of the 
genera Littorina, Assiminia, Rissoa, and Truncatella. The 
Lacune of authors are scarcely distinguishable from the Litto- 
rina littoralis; the animals are all but identical, and the two 
genera appear to be separated on conchological grounds,—the 
groove in the columella,—rather than on animal distinction. 
I think it would conduce to the interests of science if the La- 
cune were merged in the genus Littorina, and marched pari 
passu with Littorina littoralis as species. This view is adopted 
below, where I shall show, malacologically, that the difference 
between the animals of Lacuna and Littorina littoralis is 
scarcely appreciable. The so-called Lacune have only one or 
two species instead of the eight or ten of authors. 
Assiminia was established by Dr. Gray, and differs chiefly 
from the Rissoa ulve and R. subumbilicata of Montagu in 
having the eyes fixed at the extremities of the tentacula, in 
consequence of being placed on adnate pedicles of concurrent 
length. 
The Rissoe are very minute; they inhabit the littoral and 
laminarian zones; the types of the first zone are the Rissoa 
ulve and R. subumbilicata, and of the second, R. parva. 
These are true littoral Rissoe. Many minute shells, which 
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