TABLE OF CONTENTS. 



xlvii 



C II A I'T E R II, 



LEADING GROUPS OF THE EXISTING SYSTEMS OF ANIMALS. 



Skctiox 1. Great types or hrai)rhc.i of iJie aiumnl kiiujilom. 

 — Attempt to (Icline tlio i'iin<laiiiontal divisions of tlio 

 animal kinf^duni. Early classiCiL-ations. Comparison 

 of the writiiij;s of JiU'L'rent authors with the view of 

 (li'termininj; what arc natural frroups among animals. 

 The jtreat branches of the animal kingdom are eharac- 

 terized by the plan of their structure, p. 137-144. 



Section 2. Classes of animaU. — Classes arc natural 

 divisions, characterized by the manner in which the 

 plan of their respective great types is executed, and by 

 the means employed in the execution. Structure con- 

 sidered in different points of view. p. 14.3-150. 



Section 3. Orders among animals. — Orders are natural 

 groups founded upon the degree of complication of the 

 structure. Relative rank or standing among animals, 

 p. 150-155. 



Section 4. Families. — Families are natural grouji.s 

 founded \ijiiiii till' form of animals. Indefinite use thus 

 far made of the form in characterizing animals. Im- 

 portance of greater precision in that respect, p. 

 loo-lGl. 



Section 5. Genera. — Linnaius' view of genera. Latrcillc. 



Genera are natural groups based upon the ultimate de- 

 tails of structure, p. 161-1G3. 



Sectio.v C. l^tpecies. — Generally but wrongly base<l upon 

 fecundity. Hybridity, individuality, alternate genera- 

 tions, polymorphism. Species exist in nature in the 

 same manner as any other natural groups ; they are 

 based upon well determined relations of individuals to 

 one another and to the world around them, and upon 

 the proportions, the ornamentation, and the relations 

 of their parts, p. 163-170. 



Section 7. Other natural divisions among aninuds. — Be- 

 sides branches, classes, orders, families, genera, and 

 species, which express the fundamental categories of 

 the existence of animals, there occur here and there 

 further natural subdivisions, p. 170-172. 



Section 8. Successive development of characters. — In the 

 development of animals, the characteristic features do 

 not appear in the order of their systematic dignity. 

 Their succession still requires careful study. p. 

 172-176. 



Section 9. Conclusions. — Classification is a jihilosophical 

 study of the greatest importance, p. 177-178. 



CHAPTER III. 



NOTICE OF THE PRINCIPAL SYSTEMS OF ZOOLOGY. 



Section 1. General remarks upon modern systemf. — 

 Their aim and discrepancies. Desirable improvements. 

 Limits of the fundamental divisions with their respec- 

 tive classes. Rhizopoda and Infusoria. Radiata, with 

 tliree classes ; Mollusks, with three classes ; Articulata, 

 with three classes ; Vertebrata, with eight classes, 

 p. 179-187. 



Section 2. Earhj attempts to riassifi/ animals. — Lending 

 groups recognized by Aristotle, p. 187-]H;). 



Section 3. Period of Linnirus. — Linnaeus was the first 

 to present a definite system as expressing the natural 

 affinities among animals, p. 189-192. 



Sicction 4. Period of Curier, and anatomical systems. — 

 Four types among animals first recognized by Cuvier, 

 p. 193. Classification of Cuvier, p. 194. Irregularities 

 of this system, p. 195. Clas,sification of Lamarck, p. 

 196. Its principle, p. 197. Clas,sification of Delilain- 

 ville, p. 198. Compared with those of Lamairk and 

 Cuvier, p. 199. Classification of Ehrenberg, p. 200. 

 Its principle, p. 201. Cla.ssification of Bumieister, p. 

 203. Classification of Owen, p. 201. Compared with 

 those of Cuvier and von Siebold, p. 205. Growing re- 

 semblance of modern systems, p. 206. Cla.ssification of 

 Milne Kdwards, p. 207. Classification of vou Siel)old 



