FAMILY 6. TURBINACEA. 169 
Pl. CCXXI. Fig. 2. 
MarGariTA TANIATA, Sowerby, Conch. Illus. Cat., No. 1. 
Trochus bicolor, Lesson. 
Pl. CCXXI. Fig. 3. 
Margarita striata, Broderip and Sowerby, Zool. Journ., vol.iv. p.371. 
Pl. CCXXI. Fig. 4. 
Margarita UNDULATA, Sowerby, Conch. Illus. Cat., No. 12. 
LITTORINA, De Férussac. 
Testa turbinata, spiralis, solidiuscula, spira acuminata ; apertura rotunda, 
aut semilunari; columella planulata; marginibus disjunctis, labro 
acuto, interdum subexpanso. Operculum corneum, spirale. 
When the Littorine were grouped together by De Férussac, he considered 
them merely as a subgenus of Paludine ; but the important difference in 
the habits of these mollusks is alone sufficient to warrant the separation 
we have adopted. Having for the most part a solid, turbinated shell like 
others of the same marine nature, they were included by Linnzus in his 
genus Turbo; and Lamarck followed the same method of arrangement, 
forgetting that several new species, which he described_as Phasianelle, 
present a strong generic affinity with the Turbo littoreus of his prede- 
cessor. 
The shell of Littorina may be described as being turbinated, spiral, 
rather solid, and acuminated at the spire; the aperture is either round 
or semilunar, the columella is flat, and the margins are disjoined, with 
the lip acute, and sometimes a little expanded. ‘The operculum is horny 
and spiral. 
VOL. Il. Z 
