506 CYPRHAD A. 
chial plume is a large, brown, finely pectinated, half-moon- 
shaped plate of two segments, each appearmg to have a 
branchial artery. The organe générateur is large, spatulate, 
and les doubled up on the right side. The liver is dark 
brown. The coloration of these animals varies much, but in 
those individuals in which it is highly concentrated, one can 
scarcely behold a more gorgeous creature. 
It is a littoral and coralline zone species, but the animals 
and shells found in the former are of a darker hue, and the 
hard parts marked on the back with two or three black spots. 
The deep-water ones are smaller, of a pale blush colour, and 
without the dark spots ; they are varieties dependent on habitat, 
and both are abundant. 
This is the only British species, and from its close affinity 
to Ovula and Marginella, both as to its anatomy and the ex- 
ternal generalities of the soft parts, would almost serve in that 
respect as the type of either of the genera. 
The C. dullata of authors is the young Cyprea, im which 
state it shows a spire, and is more or less unrolled, bemg 
hyaline, smooth, and destitute of ribs im proportion to its 
youth. 
MARGINELLA, Lamarck. 
M. tavis, Donovan. 
M. levis, Brit. Moll. iii. p. 502, pl. 114 B. f.4,5; (animal) pl. N.N. 
£39: 
Cyprea voluia, Montagu. 
This genus is the Hrato of Risso. It is distinguished from 
Cyprea and Ovula by the short exserted spire, and of course 
is not strictly convolute; it is therefore placed by Lamarck as 
one of his Columellariade. The margins of both lips have a 
longitudinal row of minute pliciform eminences. The animal 
reflects the mantle on both sides, so as nearly to cover the 
shell; it is also formed into a free, floating, branchial canal. 
The head is little more than a vertical fissure for the issue of 
a proboscis. The tentacula are long, slender, approximate, 
with eyes on external, short, obtuse pedicles. The foot is like 
