Xii CONTENTS 



143. Classification of the Insecta 313 



144. Metamorphosis 316 



145. Apis mellifera, the Honeybee 317 



146. The Subphylum Arachnomorpha 320 



147. Argiope, an Orb Spider 322 



148. The Phylum Onycophora 323 



Chapter 17 



PHYSIOLOGY AND BEHAVIOR OF THE ARTHROPODA ... 326 



149. Molting 326 



150. Arthropod Hormones 328 



151. Patterns of Muscular Innervation 332 



152. The Flight Mechanism in Insects 334 



153. Vision ' 336 



154. Behavior 340 



155. Social Mechanisms in Insects 344 



156. Bee Language 347 



Chapter 18 



MINOR PHYLA 352 



157. Mesozoa 352 



158. Entoprocta 353 



159. Sipunculoids and Echiuroids 353 



160. The Priapuloids 354 



161. The Phoronids and Brachiopods 355 



162. The Bryozoa 356 



163. The Chaetognatha 357 



Chapter 19 



THE PHYLA HEMICHORDATA AND ECHINODERM.\TA ... 360 



164. The Phylum Hemichordata 360 



165. Classification of the Phylum Echinodermata . . . 364 



166. Asterias forhesi, a Typical Five-rayed Starfish . . 364 



167. Class Asteroidea, the Starfish 370 



168. Class Crinoidea, the Sea Lilies 370 



169. Class Holothuroidea, the Sea Cucumbers 372 



170. Class Echinoidea, the Sea Urchins, Heart 



Urchins and Sand Dollars 373 



171. Class Ophiuroidea, the Brittle Stars 375 



172. Relationships among Echinoderm Classes 375 



173. Relationships among the Hemichordata, 



Echinodermata, and Other Phyla 377 



