INDEX. 



499 



of, 438-440 ; of vertebrates, 

 452 ; importance of, in classifi- 

 cation, 453. 



Smell, sense of, and its organ, 

 188-193. 



Special sense, relation of, to gen- 

 eral sensibility, 94-96. 



Spinal column, 226. 



Spinal cord, 45-49. 



Spinal nerves, 46, 54. 



Spinal or reflex system, function 

 of, 66. 



Sponges, skeletal deposits in, 

 469. 



Structure of vertebrates, general 

 plan of, 249. 



Sudorific glands, 437 



Taste, sense of, and its organ, 

 193-198. 



Taxonomy, definition of, 9. 



Teeth in vertebrates, 295-310 ; 

 mammalian, 296; composition 

 of, 297 ; kinds of, 297 ; varia- 

 tion of, 298 ; relative size of, 

 298 ; number of, and relative 

 number of kinds of, 298 ; mo- 

 lar, structure of, 300 ; origin 

 of structure of herbivorous, 

 302 ; of whales, 304 ; of birds, 

 305 ; of reptiles, 305 ; origin 

 of mammalian, 308 ; of fishes, 

 308. 



Temperature regions, definition 



of, 474-477- 



Thalamus, 33, 41. 



Theca, 468. 



Three kingdoms of Nature, rela- 

 tion of the, 1-8. 



Touch, sense of, and its organs, 

 19S-204. 



Ungulates, classification of, by 



foot structure, 257. 

 Urine, composition of, 429, 430. 



Veins, 382. 



Vibrations, perception of, 96. 



Vision, 122-155 I nrst ' aw °f. 

 122 ; second law of, 126 ; third 

 law of, 144 ; two fundamental 

 laws of, 149 ; erect, 129 ; bin- 

 ocular, 142 ; double, 142 ; sin- 

 gle, 143 ; limitation of, 151. 



Visual purple, 121. 



Voice, 204-218 ; simple, 204 ; 

 singing, 210; speaking, 211; 

 comparative physiology of, 



213 ; in birds, 214 ; in reptiles, 



214 ; in fishes, 214 ; in arthro- 

 pods, 216. 



Waste tissue, 290, 420. 

 Whales, mouth armature of, 

 304 ; mode of feeding of, 305. 

 Wrist joint, 253. 



Zoological temperature regions, 



474- 

 Zoology, definition of, 8-10 ; de- 

 partments of, 10. 



THE END. 



