APPENDIX B 



THE MAJOR GROUPS OF ANIMALS 



Vertebrata — the backboned animals. — This very large group 

 includes the mammals, birds, reptiles, amphibians and fishes 

 which together are represented by about fifty thousand different 

 species. The structure is very complex, and the size ranges from 

 a length of no feet in the great blue whale as found in the Antarc- 

 tic down to about three-quarters of an inch in the smallest adult 

 fish. But all vertebrates are relatively large, and the average size 

 is far larger than in any other group. Vertebrates are found 

 everywhere, in every region and from the highest mountain tops 

 down to the ocean floor. The animal from the greatest depth 

 in the sea at which animals have been found (19,806 feet) is a 

 fish. Most vertebrates live on land. The fishes, however, live 

 chiefly in the sea; also living and breeding in the sea are the 

 whales, except for a few fresh water dolphins in South America 

 and Asia, ana the sea-snakes. (Fig. 2., p. 5.) 



Cephalochorda — Am-phioxt&s (Branchiostoma) and its allies. — 

 This is a very small group including only a few species which 

 look like small colorless semitransparent fishes headless and 

 pointed at each end. They live partially buried in sand. They 

 are found only in the sea in shallow water and at moderate 

 depths, and are widely distributed, though very local. 



Balanoglossida. — A small group confined to the sea wherein 

 they are very widely distributed. Like sponges, they have a 

 disagreeable and usually strong smell which sometimes imparts a 

 flavor to the fishes that feed on them. (Fig. 94, p. 175, young.) 



Cephalodiscida. — A very small group including a very few 

 species of two quite different types {Ce-phalo discus [fig. 61, p. in] 

 and Uab do-pleura [fig. 63, p. in]). They are found only in the 

 sea in shallow water and in water of moderate depth and are 

 widely distributed, though apparently very local. 



TuNicATA — the sea-squirts, sea-peaches, pyrosomas and their rela- 

 tives. — This is a large and highly diversified group entirely con- 

 fined to the sea. The various species are found in all seas at all 

 depths, but most of them live in shallow water. Some live 

 attached to the bottom, while others float freely in the water. 



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