362 Mr. W. Clark on the Littorinide. 
a minute orifice; the female is oviparous; the antepenultimate 
whorls are always flat-in this species, being a condition resulting 
from the shape and size of the ovarium, which is only adapted 
for ova; it is however much more prolific than the Littorina rudis 
and varieties. 
This is the common edible periwinkle of the London markets, 
and the only one, as the females of the Z. rudis and all its va- 
rieties are viviparous, and cannot be used for food in consequence 
of the grittiness arising from craunching the testaceous pull ; it 
is found in all’situations often exposed to the full influences of 
an open sea, but more usually in estuaries and muddy inlets, 
which are also the habitats of certain varieties of the L. rudts ; it 
grows to 13 inch in length and | inch diameter. 
Littorina rudis, Donovan. 
L. patula, L. neglecta, L. fabalis, L. saxatilis, and, 
sub fide Forbes, LZ. palliata, Xc., 
This well-marked species has nearly the same organs as L. fit- 
torea ; | have compared the nervous ganglions and other internal 
parts of both forms, without finding distinction. To enumerate the 
greater part of the other organs, in comparison with those of L. 
littorea, would be a repetition; I will only mention the essential 
specific distinction, which is, that in the females of this species 
the large bulky ovarium is usually filled with strings of testaceous 
pulli ; that is, if they are examined at the season when, O! Alma 
Venus, thy votaries are “ perculse corde tua vi,’ the ovaries 
fill up the tumid antepenultimate volutions. The markings and 
colours of the animal have the same character as those of Litto- 
rina littorea, except that they are much less intense ; but though 
closely allied, it is very particularly distinguished by the much 
higher littoral level of its habitat, the greater tumidity of the 
volutions, colour, and above all by the very different ovarium, its 
contents and mode of reproduction. It rarely exceeds an inch in 
length and three-quarters of an inch im diameter. 
To describe the varieties enumerated above, which are the 
pseudo-species of authors, would be to say, that the organs of all, 
both internal and external, do not vary im the slightest degree 
in form ; the only differences are modifications of colour, size, and 
in the striz, depending entirely on habitat. The L. rudis, L. tene- 
brosa, L. zonaria and L. rudissima are usually inhabitants of the 
estuaries and muddy oozes, and rarely exposed to the full action 
of an open sea. 
We earnestly recommend naturalists in their respective loca- 
lities to consign the four species above-named to basins of water, 
together with all the dwarf varieties inhabiting the crevices of 
L. tenebrosa, L. zonaria, L. rudissima, L. jugosa, 
auctorum. 
