TRACHELIPODA. 73 



XL fig. 22. Ovate, transversely grooved, reddish fulvous; 

 volutions convex ; apex with one tubercle. Three inches and 

 a half long. Inhabits the Mediterranean sea. 



FAMILY 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.— STROMBU S.—Linnceus. 



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 ; aperture provided with a long narrow horny operculum. 



Strombus auris JJiance. — Diana's Ear Strombus. Plate 

 XT. 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 quar- 

 ter long. Inhabits the Indian ocean. 



Genus 24— PTERO CERA.— ZamarcA-. 



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 XT. 

 fig. 24. Ovate, tuberculated^, with six digitated, canaliculated 

 rays, which are closed over in the adult shell ; outer lip inter- 

 nally striated. Six inches and a half long, exclusive of the digi- 

 tated lobes. Inhabits the Indian ocean. 



Genus 25.— ROSTELLARTA.— iawarc/^. 



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. 



