204 CLASS III. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
De Blainville still refuses to allow of the Pterocere being distinguished 
as a genus, including them after the manner of Linnzeus with the Strombi ; 
he is, however, the only author who has failed to appreciate this arrange- 
ment. 
The shell of Pterocera may be described as being somewhat turrited, 
ovately-oblong, and ventricose, the last whorl being very considerably 
larger than the others ; the aperture is oblong; the columella, which is 
frequently striated or lined, ends in a long recurved canal, and the lip, in 
which the sinus is strongly developed, is thickened and expanded into a 
clawed or digitated wing, increasing with age, and often striated in the 
interior like the columella. The operculum is horny, thick, oblong, and 
acute at the base. 
Examples. 
Pl. CCXLVII. Fig. 1. 
Prerocera ruGosa, Sowerby, Jun., Thesaurus Conchyliorum, Part II. 
pl.11. fig. 9 and 10. Martini, Conch., vol. ili. pl. 87. f. 856 and 857. 
Pterocera chiragra, var., Lamarck. 
Ungula Diaboli, Martini. 
Pl. CCXLVIII. Fig. 1. 
Prerocera MULTIPES, Deshayes, Régne Animal (Cuvier), Mollusques, 
pl. 61. f. 3. and 3, a. Sowerby, Jun., Thesaurus Conchyliorum, 
Part. HH.) pl. J1.. fie:8. 
Strombus multipes, Chemnitz, Conch., vol. x. pl. 157. f. 1494 and 1495. 
Pterocera millepeda, var., Lamarck. 
Pl. CCXLVIII. Fig. 2. 
Prerocera crocea, Nobis, Sowerby, Jun., Thesaurus Conchyliorum, 
Part ilplil dig:4. 
Strombus novem dactylis, Chemnitz, Conch., vol. x. pl. 155. f. 1479. 
? 
Pterocera elongata, 
