Page:Popular Science Monthly Volume 50.djvu/65

Rh home his hand was caught between shell and rock, and so firmly-held by the animal that he could not escape the rising tide, and was drowned.

The pearly lining of the abalone is richly shaded with all colors of the rainbow, an opalescent green often predominating. Themother-of-pearl is composed of undulating layers. The iridescence is caused by minute lines reflecting different spectra.

Some members of the snail family, with their world-wide reputation for slowness, have made amazing progress in the ascending scale. They have gone so far as to develepdevelop [sic] from the gills, with which they breathed in the water, lungs suitable for air-breathing, and have come to enjoy the pleasures which a life on terra firma affords. You can find them in the woods or in your garden, thrusting out their inquisitive little heads and investigating everything with their eye-tipped feelers. Some snails, after trying the experiment of a land life, have decided that on the whole a water life is preferable, and gone back to live there, where they have developed gills again, but of a different kind from the original ones.

There are sea snails, pond and river snails, as well as land snails. Many of them are carnivorous and can bore into other shells with their lingual ribbons. The hole usually strikes a muscle, when the shell gapes open, and his snailship enters and devours his prey.

Some kinds of snails, especially the land group, can live for a great length of time without food. A snail was fastened to a card and put in the British Museum in 1846. Four years afterward a discoloration appeared on the card, showing that he had been moving about. He was taken out, immersed in warm water, and was soon quite lively.

In creeping about, the snails always leave a track of mucus, which glistens when it is dry. It is in this mucus that they immure themselves for their long winter's nap, sometimes making several layers or partitions over the opening to the shell.

In the middle ages snail shells were worn as amulets, protecting the wearer against certain diseases as well as witchcraft.

Prof. J. S. Kingsley says of one North American species (Helix harpa): "In motion it is exceedingly graceful, at times poising its beautiful shell above its body and twirling it around, . . . again hugging its pretty harp close to its body."

The shells of the common wood snails are quite transparent