506 



chial plume is a large, brown, finely pectinated, half-moon- 

 shaped plate of two segments, each appearing to have a 

 branchial artery. The organe generateur is large, spatulate, 

 and lies doubled up on the right side. The liver is dark 

 brown. The coloration of these animals varies much, but inr 

 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 sheDs 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 Maryinella, 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. bullata of authors is the young Cypraea, in which 

 state it shows a spire, and is more or less unrolled, being 

 hyaline, smooth, and destitute of ribs in proportion to its 

 youth. 



MARGINELLA, Lamarck. 



M. L^VIS, Donovan. 



M. Icevis, Brit. Moll. iii. p. 502, pi. 114 B. f. 4, 5 ; (animal) pi. N.N. 



f. 8, 9. 

 Cyprcea valuta, Montagu. 



This genus is the Erato of Risso. It is distinguished from 

 Cyprcea and Ovula by the short exserted spire, and of course 

 is not strictly convolute ; it is therefore placed by Lamarck as 

 one of his Columellariadce. 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 kmg, slender, approximate, 

 with eyes on external, short, obtuse pedicles. The foot is like 



