16 ZOOLOGY. 



of the animal kingdom, and may be regarded as rudely in- 

 dicating the blood-relationship or pedigree of animals. It 

 differs in some important respects from the classifications 

 given in the books ordinarily in use by American students. 

 It is a question whether the Tunicata should not form a 

 ninth branch, and stand next below the Vertebrates. 



Some authors retain the four types of Cuvier, but it 

 should be remembered that since Cuvier's classification was 

 proposed in 1812 our knowledge has been greatly extended. 

 The microscope has revealed an immense mass of new mi- 

 croscopic forms, and many facts regarding the structure and 

 development of the larger forms. The embranchments of 

 Cuvier are in all cases, except the Vertebrates, unwieldy, het- 

 erogeneous, and, in the light of our present knowledge, un- 

 natural assemblages of animals. New discoveries do away 

 with old systems, and the classifications adopted by differ- 

 ent authors represent the standpoint from which they re- 

 gard the system of nature. It is not of so much consequence 

 to the student to know what the system may be, as to learn 

 the leading facts of animal morphology and development. 



Palaeontology. With a thorough knowledge of the anat-* 

 omy of animals and their classification, the student is pre- 

 pared to study the remains of extinct animals, to restore so 

 far as possible their forms, and to classify them. With a 

 knowledge of the hard parts of existing animals, and of the 

 interaction of the tendons, ligaments, muscles, and bones, 

 the palaeontologist can, in accordance with the law of cor- 

 relation of parts, refer fossils to their respective orders, 

 families, genera, or species. 



Zoogeography, or geographical distribution, is the study 

 of the laws of distribution of animals over the surface of 

 the earth or over the bottom of the sea. The assemblage 

 of animals inhabiting any area is called a fauna. Thus we 

 have an arctic fauna, a tropical fauna, a North American 

 fauna, or Australian fauna. The fauna of the ocean is sub- 

 divided into different subordinate faunae. 



