368 



THE COMMON SPIDER-SHELL. 



overlapping each other like the tiles of a house, or the successive steel layers of a 

 carriage-spring. 



Some species of Strombs attain a considerable size, and are much used in the arts, 

 as, for example, the GIANT STROM B, or FOUNTAIN SHELL (Strombus gigas), one of the 

 West Indian species, which sometimes attains the weight of four or five pounds, and is 

 imported into Europe in several thousands for the use of engravers, who cut the well- 

 known cameos from its beautifully tinted substance. Three hundred thousand of these 

 shells were brought to Liverpool alone in a single year. As the animal increases in 

 age, it gradually fills up the hollow apex and spines with solid matter, and thus materi- 

 ally adds to the weight of the shell without improving its value to the engraver. In 

 some parts of the world, such as Barbadoes, the Giant Stromb is eaten, and sold regularly 

 for that purpose. Pearls of a delicate pink color have sometimes been found in 

 this shell, but their occurrence is not frequent, probably on account of the careless and 

 unobservant habits of the negroes who clean the shells. Pearls are also found in other 

 species belonging to this genus. 



The teeth of the Strombs are extremely beautiful and most complicated, but cannot 

 well be described without the aid of illustrations. 



The color of the Three-horned Stromb is brown and yellow of different shades, 

 v hly mottled with pale saffron. Its average length is about four inches. 



COMMON SPIDER SHELL. - 

 Pteroceras lambis. 



QRANQED MOUTHED SPIDER-SHELL, 

 Pteroceras aurantlas. 



THE two species represented in the illustration derive their popular names from the 

 gently spider-like contour of their form. 



When adult, the outer lip is furnished with several horny appendages, always curved, 

 and not precisely of the same shape in the same species, although the general character 

 of their form is sufficiently well marked to distinguish the species. One of these horns 

 is always close to the spine, and is rolled in such a manner as to form a posterior canal. 

 About ten species of these animals are known, and seem to be confined to the Chinese 

 and Indian seas. 



The COMMON SPIDER-SHELL is seen on the left of the illustration, the animal being 

 represented in the act of crawling, the foot being applied to the ground, the operculum 

 trailing behind, and the two eyes in their long footstalks projecting in front. The 

 color of this shell is very handsome, consisting of boldly mottled chestnut, like the hue 

 of old rosewood, variegated with white, and traversed by lines of orange. The interior 

 of the shell is pale brown, with a dash of yellow. The average length is three or four 

 inches. 



