44 MOLLUSCA. TRACHELIPODA. 



ribs, somewhat alternately larger and longitudinally wrinkled, the 

 rugae sometimes scaly ; colour whitish yellow, marbled with red- 

 dish or purplish brown or green ; inside silvery. 2 inches long. 

 Inhabits Indian Ocean Chemnitz, v. pi. 177, fig. 1758, 1759. 

 T. setosus, Lam. Shell ovate, ventricose, imperforate, thick, trans- 

 versely and deeply sulcated, variegated with white, green, and 

 fuscous ; furrows transversely striated ; whorls rounded, spire 

 short ; lip crenulated, and aperture silvery. 2 inches long. In- 

 habits Indian seas Humph. Mus. pi. 19. fig. C. 



T. pica, Lin. Shell orbicular, conical, ventricose, smooth, and the 

 whorls rounded; widely and deeply umbilicated ; thick, ponde- 

 rous, with black spots and longitudinal zigzag stripes ; umbilicus 

 with a tooth at the orifice ; inside silvery. 2 to 3 inches long. 

 Inhabits American and Indian seas. Bonan. 3, fig. 29, 30. 



T. cidaris, Lin. Shell smooth, compressed, globose, subimperf orate, 

 variously coloured and banded ; body whorl ventricose ; aperture 

 compressed, silvery ; spire short, obtuse. 1 ^ inch long. Inha- 

 bits coasts of China and India. D'Argenv. pi. 6. fig. B, O. 



T. littoreus, Lin. The Periwinkle. Shell subovate, acute, imper- 

 forate, transversely striated ; the last whorl ventricose ; margin 

 of the pillar flat. Nearly an inch long. Inhabits European 

 coasts. B. Brown's Illust. pi. 46, fig. 1, 9. 



This very common shell is generally from three quarters of an inch to an inch 

 long, and nearly equally broad, thick, with five or six whorls, of which the body 

 whorl is larger than all the others together. When full grown it is nearly smooth 

 and of a uniform brownish colour, but younger shells are more distinctly striated 

 transversely, and variously marked with bands of purplish brown, white, yellow 

 or red. It is extremely abundant on the coasts of Britain, and is sold in the mar- 

 kets. 



Gen. 41. MONODONTA, Lam. Turbo, Lin. 

 Shell oval or conoid ; aperture entire, rounded, with the border 

 above disunited ; columella arched, and truncated at the base ; 

 an operculum. 



The genus seems to connect the Trochi and Turbones. They are distinguished 

 from the trochi by their opening being more rounded, that is not depressed, and 

 from the turbines by their pillar being truncated at the base. All are marine shells, 

 oblique, with the spire more or less elevated, smooth or tuberculous. The animal 

 has an elliptic short ciliated foot, furnished laterally with some long subciliated fila- 

 ments ; two long tentacula, covered with piliform filaments ; the eyes at their base 

 on short pedicles ; and a thin horny orbicular operculum attached to the foot. 



M. pagodus, Lam. Shell conical, oblique, imperforate, with echi- 

 nated tubercles, longitudinally ribbed and transversely sulcated, 

 brownish gray; the ribs with compressed tubercles extending 

 over the margin of the spire ; base marked with granulated striae. 

 2 inches long. Inhabits Indian Ocean. D'Argenv. pi. 8, fig. A. 



M. tectum, Lam. Shell oval, ventricose, subperforate, striated trans- 

 versely and longitudinally plaited ; spire depressed ; colour white, 

 with transverse rows of purplish brown spots. 8 lines long. In- 

 habits West Indian seas D'Argenv. pi. 6, fig. Q. 



