FAMILY 9. ALATA. 203 
Pl. CCXLVI. Fig. 5. 
Rosreviaria pes Pericanr, Lamarck, Anim. sans vert., vol. vii. p. 193. 
Martini, Conch., vol. iii. pl. 85. f. 848 to 850. 
Cochlea pentadactylos, Pliny. 
Turbo pentadactylos, Bonanni. 
Strombus rostratus, Gualter. 
Vespertilio spinosus, Seba. 
Strombus pes Pelican, Linnzeus. 
Alata pes Pelicani, Martini. 
Aporrhais pes Pelican, Sowerby, Jun. 
PTEROCERA, Lamarck. 
Testa subturrita, ovato-oblonga, ventricosa, anfractu ultimo valdé ma- 
jore ; apertura oblonga; columella sepé striata, in canalem elonga- 
tum, recurvum, desinente ; labro sinu distincto, incrassato, in alam 
digitatam ztate ampliato, fauce plerumque striata. Operculum cor- 
neum, crassum, oblongum, basi acutum. 
The Pterocere were arranged by Lister, Gualter, Aldrovand and other 
of the early naturalists, together with the digitated varieties of Rostellaria, 
under the old Aristotelian title of Aporrhais. Linneus confounded them 
with the Strombi; and it was not until the regular introduction of the 
genera we have adopted, that a clear and correct distribution of these 
mollusks was established. Their shells are very peculiar in their manner 
of growth, and differ essentially from those of any genus, excepting Rostel- 
laria; when nearly completed the lip becomes very widely expanded, 
passing in many instances completely over the top of the spire, and the 
margin extends into a number of canaliculated claws or digitations. Even 
the columella terminates in a canaliculated claw, and there is often one 
or more of these claw-like developments between the canal and the labral 
sinus. 
2 pez 
