ECONOMIC ZOOLOGY. 



397 



that have held out any sort of promise of pleasure 

 or nutrition. Notwithstanding this, very few of the 

 invertebrates have been given a wide place in his bill-of- 

 fare. The lowest forms eaten are the "trepangs" (holo- 

 thurians) which are used in great numbers by the Chinese. 

 In the branch of mollusks the oyster is at the head in 

 importance. There are also a number of marine and 

 fresh-water clams and mussels which are used in smaller 

 numbers. Some species of gasteropods (snails) are prized 

 in certain parts of the world. It is believed that the 

 mussels were an important article of food to some tribes 

 of North American Indians, and to some of the peoples of 

 the old w r orld when they were in a corresponding stage 

 of development. Among the arthropods the lobster 

 comes first in importance, although it has been fished 

 to such an extent that the output is rapidly diminishing 

 and the size of specimens is steadily decreasing. Cray- 

 fish, shrimps, prawns, and crabs are also used to some 

 extent. The great class of insects furnishes only the 

 honey of the honeybee. 



Every class of vertebrates furnishes food species. The 

 amphibians and the reptiles stand lowest in this respect. 

 The frogs and turtles are their only edible representatives. 

 The fishes, the birds, and the mammals furnish the staple 

 meat foods. A very large per cent, of the fishes are 

 recognized as edible. Many species of the sharks, even, 

 are prized although they are actively carnivorous, and 

 the carnivorous animals have usually not been regarded 

 as good to eat. Many species of birds have been eaten, 

 but those that rank as of real importance belong chiefly 

 to the Gallinae, the Columbae, and the Anseres. These 

 three orders of birds supply to man hundreds of millions 

 of dollars worth of his choicest food annually. 



