to become intimately acquainted with 

 the Littorinas, or periwinkles, for they 

 cover the rocky shores everywhere, mil- 

 lions of their rounded shells clinging to 

 the rocks when the tide goes out. They 

 feed on the algae which grows on the 

 shore. They are found in both brackish 

 and fresh water. The common periwin- 

 kle (Littorina littorea) is extremely 

 abundant on the shores of southern Eu- 

 rope and the northern part of the United 

 States. In England it is used as an ar- 

 ticle of food and it is said that nearly 

 two thousand tons are gathered annually 

 and that a thousand persons are em- 

 ployed in capturing it. In London and 

 other large cities they are sold on the 

 street, the animal being picked out with 

 a pin. It is used for bait in some of the 

 fisheries and the oystermen plant many 

 bushels on their oyster beds yearly to 

 keep the seaweeds from accumulating. 

 From these facts it will appear that this 

 periwinkle is of considerable economic 

 importance. All of the species are am- 

 phibious, living for a long time out of 

 the water. 



Of all the gastropods none excel the 

 curious Xenophora in point of oddity. 

 The shell is in general form like that of 

 the top shell, but as it grows it attaches 

 to itself small stones and pieces of shell, 

 so that when the animal is fully grown 

 it looks like a heap of dead shells and 

 pebbles. This habit is in all probability 

 to conceal the animal from its enemies. 

 They are called ''carriers" and the indi- 

 viduals with shells attached to their 

 house are called Conchologists, while 

 those with stones attached are called 

 Mineralogists. The fragments of shells 

 are attached with concave sides upward 

 so as not to impede the animal during 

 locomotion. The carriers are not able 

 to glide like other moUusks, their feet 

 being very small. They progress by lift- 

 ing the front part of the foot to an ob- 

 ject and then drawing the hind part 

 toward it. In this way they jump or 

 scramble along in a ludicrous manner. 



Related to the "carriers" are the slip- 

 per-shells (Crepidula), the horse-hoof 

 shell (Hipponyx) and the bonnet-limpet 

 (Capulus). The slipper shells are found 

 in many parts of the world and are par- 

 ticularly abundant on the Atlantic and 

 Pacific shores of the United States. The 



shell is flat and somewhat limpet-like, 

 and across one end, near the apex, is a 

 little shelf which gives it the appearance 

 of a Chinese slipper. They adhere to 

 stones, shells, crabs and any submerged 

 object, and modify the form of their 

 shell to fit the inecjualities of their rest- 

 ing place. Thus a Crepidula on a Pec- 

 ten shell will be ribbed while the same 

 species on a stone will be perfectly 

 smooth. Frequently they may be seen 

 piled one upon another in tiers of six or 

 more. The animal generally feeds on 

 seaweed but has been known to eat 

 other mollusks. The bonnet limpets also 

 belong to this family, as do the cup- 

 and-saucer limpets (Calyptraea). 



The family Strombidae contains many 

 large and interesting shells. The animal 

 is very powerful and is able to leap ^ 

 considerable distance. Mr. Arthur 

 Adams, a celebrated conchologist, thus 

 describes its method of leaning: "Plant- 

 ing firmly its powerful, narrow oper- 

 culum against any resisting surface, it 

 insinuates it under the edge of its shell 

 and by a vigorous effort, throwing it- 

 self forwards, carrying its great heavy 

 shell with it, the animal rolls along in a 

 series of jumps in a most singular and 

 grotesque manner." The eyes of the an- 

 imal are greatly developed. The shells 

 of Strombus vary greatly in form and 

 color. In some the outer lip is simply 

 turned over while in others it is modified 

 by little spines or projections. The aper- 

 ture is frequently colored pink, purple 

 or yellowish. The large Strombus gigas 

 is used in carving cameos, its shell being 

 made up of several layers of different 

 colors. It is also ground to powder for 

 the manufacture of porcelain and in the 

 West Indies the animal is used as an 

 article of food. 



The Auger or steeple shells, belonging 

 to the family Terebridae, have long been 

 objects of interest not only to the nat- 

 uralist but to the layman who places 

 them in his house as ornaments. There 

 are about two hundred species which are 

 found in many parts of the world, al- 

 though chiefly confined to tropical seas. 

 The shells are very long and are com- 

 posed of many tightly wound whorls, 

 which are smooth in some species and 

 longitudinally ribbed in others. They 

 vary also in color, being yellowish, gray- 



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