MOLLUSCA. 
395 
vex; apex with one tubercle. Three inches and a half long. 
Inhabits the Mediterranean sea. 
TRIEE IV.-ALATA. 
Shell provided with a canal of greater or less extent, at the 
base of the aperture; the right lip changes its form as the 
animal advances in age, and is provided with a sinus at the lower 
part. 
Genus 23.—S TROMB U S.— Linnaeus. 
Generic Character. — Shell ventricose, base terminating in a 
short, truncated, emarginated canal; right lip dilating with age 
into a simple, entire wing, lobed or crenulated above, and pro¬ 
vided with a sinus beneath, separated at the base from the canal 
or notch. 
Strombus auris Dianae. — Diana’s Ear Strombus. 
Plate LXXXIV. fig. 23. 
Oblong-ovate; spire acute, tuberculated, and transversely 
striated; base recurved; outer lip thick; anterior lobe with a 
finger-like termination. Three inches and a quarter long. 
Inhabits the Indian ocean. 
Genus 24.—PTEROCERA.— Lamarck. 
Generic Character. —Shell oblong-ovate, ventricose, terminat¬ 
ing in a lengthened canal; outer lip dilating with age into an 
expanded, rayed, or digitated wing, with a sinus near the base ; 
spire short. 
Pterocera chiragra. — The Knotty Pterocera. 
Plate LXXXIV. fig. 24. 
Ovate, tuberculated, with six digitated, canaliculated rays, 
which are closed over in the adult shell; outer lip internally 
striated. Six inches and a half long, exclusive of the digitated 
lobes. Inhabits the Indian ocean. 
Genus 25. —ROSTELLARIA.— Lamarck. 
Generic Character. —Shell fusiform or sub-turrited, termi¬ 
nated below by a beaked canal; outer lip entire in some species, 
and dentated in others, more or less dilated by age; with a 
sinus near the canal. 
