XX CONTENTS. 



Page 



§ 3. Gasteropoda 227 



4. Structure and formation of the Shells of Mol- 



lusca 230 



5. Pteropoda 257 



6. Cephalapoda 258 



Chapter IV. — Articulata 268 



§ 1. Articulated animals in general 268 



2. Annelida 269 



3. Arachnida 282 



4. Crustacea 286 



Chapter V. — Insects 296 



§ 1, Aptera 296 



2. Insecta alata 299 



3. Developement of Insects 302 



4. Aquatic Larvae 309 



5. Terrestrial Larvae 311 



6. Imago, or perfect Insect 317 



7. Aquatic Insects 335 



8. Progressive motion of Insects on land 338 



9. Flight of Insects 344 



Chapter VI. — Veutebrata 361 



§ 1. Vertebrated Animals in general 361 



2. Structure and Composition of the Osseous 



Fabric 365 



3. Formation and developement of Bone 375 



4. Skeleton of the Vertebrata 386 



Chapter VII.— Fishes 408 



Chapter VIII. — Reptilia 435 



§ 1. Terrestrial Vertebrata in general 435 



2. Batrachia 436 



3. Ophidia 447 



4. Sauria 457 



5. Chelonia 463 



