210 CLASS III. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
Examples. 
PIACCLIE., Fig. I. 
CassIDARIA ECHINOPHORA, Var. (notatu digna), Lamarck, Anim. sans vert., 
vol. vii. p. 215. 
Buccinum echinophorum, Linnzeus. 
Cassidea echinophora, Bruguiére. 
Pl. CCLII. Fig. 2 and 3. 
CassipariA TyrrHena*, Lamarck, Anim. sans vert., vol. vii. p. 216. 
Chemnitz, Conch., vol. x. pl. 153. f. 1461 and 1462. Encyclopédie 
Méthodique, pl. 405. f.1. a,b. Kiener, Iconographie des Coquilles 
vivantes, pl. 1. f. 1. 
Buccinum cassideum Tyrrhenum, Chemnitz. 
Cassidea Tyrrhena, Bruguiére. 
Cassidaria echinophora, var., Philippi. 
ONISCIA, Sowerby. 
Testa oblonga, subcylindrica, spira brevi, apice interdum obtusiusculo, 
in canalem brevissimum desinens ; apertura angusta, longitudinali, 
labro columellari granuloso, latissimé expanso, labro externo incras- 
sato, irregulariter denticulato, ad medium leviter coarctato. 
* The shell represented in our plate in illustration of this species is undoubtedly the true 
Cassidaria Tyrrhena of Lamarck, agreeing as perfectly with his description, as with the figures 
he refers to. The shell figured in Sowerby’s ‘“ Genera’’ under this title is but a common 
variety of the Cassidaria echinophora, another very singular variety of which, belonging to 
H. Cuming, Esq., we have also given in our plate (fig. 1.). There are many varieties of the Cas- 
sidaria Tyrrhena, and yet more of the Cassidaria echinophora; and it is therefore to be re- 
gretted that Philippi should have confounded them together. There is less difficulty in de- 
termining the limit of a species than of a genus, though the determination of both may be 
equally artificial, and equally a matter of fancy. 
