274 CIVIC BIOLOGY 



I never got an oyster. As soon as they grew to amount to 

 anything the oyster pirates came along and cleaned them np 

 in a night. So I had to give it up." 1 



Classification. Our common mollusks may be classified into three 

 main groups : 



1. Lamellibranchs (lamella-gilled) : Clams, mussels, oysters, scallops, 



bivalves, all are aquatic (marine and fresh-water). All the great 

 food mollusks belong in this class, because their gills enable them to 

 filter out and feed upon the inexhaustible supply of algse and other 

 organisms floating in the water. 



2. Gastropods (stomach-footed) : Snails, conchs, periwinkles, aba- 

 lones, typically coiled univalve shells, and many shell-less forms 

 (garden slugs) are marine, fresh-water, and terrestrial. Most gastropods 

 are carnivorous, but a number are vegetarian, like the edible snails, 

 the slugs, and the periwinkles and abalones, which feed upon the algae 

 arid seaweeds of the bottom. 



3. Cephalopods (head-footed): Squids, cuttlefishes, devilfishes, octo- 

 puses, nautilus, are all marine, the molluscan over- (or under-) lords of 

 the ocean. The cephalopods are all carnivorous, and many of them are 

 used for food by oriental peoples. Our common squids, used now for 

 fish bait, are good food mollusks. 



Typical problems and life histories. While schools along the seacoasts 

 have the advantage, the mollusks of our rivers, lakes, and ponds, and 

 even of our woods and gardens, offer problems of no mean interest. 



Oysters. Ostrea virginica is the native oyster of the Atlantic coast 

 from Cape Cod to the Gulf of Mexico. It has the reputation of being 

 the finest edible oyster in the world. A small, starveling variety, the 

 " coon oyster," forms extensive natural beds throughout the salt-marsh 

 sedges and mangrove swamps of the Southern states. A small but 

 delicious species, 0. lurida, is native to the American Pacific, and 

 young 0. virginica, since 1870, have been shipped across the continent 

 to grow and fatten in the favored coves of the Pacific coast. Almost 

 the entire Pacific coast line, however, from Puget Sound to Mexico, is 

 a waste of desert sand, unindented and open to the ocean front, with 

 line after line of huge beach combers out as far as the eye can reach 



terrific instead of " pacific," and not at all suited to the oyster. The 

 United States Bureau of Fisheries has made repeated experiments in 

 colonizing Atlantic oysters in favored places along the Pacific, but, 



1 Experience of a shore owner on the Chesapeake. 



