xvi CONTENTS 



SECTION IX 



PAGE 



Phylum Eehinodermata 375 



1. Example of the Asteroidea Asterias rubens or Anthenea flavescens. 375 



2. Example of the Echinoidea Strongylocentrotyg or .Echinus . . 393 



3. Example of the Holothuroidea Cucumaria or Colochinix . . 401 



4. The Crinoidea Antedon rosacea 405 



5. Distinctive Characters and Classification .410 



Systematic Position of the Examples 41 4 



6. General Organisation 415 



SECTION X 



PHYLUM ANNULATA 439 



Class I. Chsetopoda 439 



1. Examples of the Class 440 



i. Nereis dumerilii . . . 440 



ii. Lumbricus 454 



2. Distinctive Characters and Classification 464 



Systematic Position of the Examples 466 



3. General Organisation 467 



Appendix to the Chsetopoda Class MyzostOHlida .... 489 



Class II. Gephyrea 491 



1. Example of the Class Sipuncvlus nudus 492 



2. Distinctive Characters and Classification 495 



3. General Organisation 496 



Class III. Archi-annelida . 503 



Class IV. Hirudinea 506 



1. Example of the Class Hirudo medicinalis and H. aiistr<di* . 506 



2. Distinctive Characters and Classification 515 



Systematic Position of the Example 517 



3. General Organisation 517 



4. General Remarks on the Annulata 523 



SECTION XI 



PHYLUM ARTHROPOD A 526 



Class I. Crustacea 526 



1. Examples of the Class 526 



i. Apus or Lepidurus 526 



ii. Astacus fluviatilis 539 



2. Distinctive Characters and Classification 561 



Systematic Position of the Examples 569 



3. General Organisation 570 



Affinities and Mutual Relationships 602 



Appendix to Crustacea Class Trilobita 604 



Class II. Onychophora 607 



Class III. Myriapoda 614 



1. Distinctive Characters and Classification 614 



2. General Organisation 615 



