CONTENTS xvii 



PHYLUM ARTHROPODA continued. PAQE 



Class III. Myriapoda 598 



1. Distinctive Characters and Classification 598 



2. General Organisation 600 



Class IV. Insecta 602 



1. Example of the Class Pcriplaneta orientalis or P. americana . 603 



2. Distinctive Characters and Classification 615 



Systematic Position of the Example . . . . . .621 



3. General Organisation 621 



Class V. Arachnida 637 



1. Example of the Class Euscorpio or Buthus . . . . . 638 



2. Distinctive Characters and Classification 644 



3. General Organisation 646 



Appendix to the Arachnida the Pycnogonida, Linguatulida, 



and Tardigrada 657 



Relationships of the Air-breathing Arthropoda .... 659 



SECTION XII 



PHYLUM MOLLUSCA 663 



Class I. Pelecypoda 663 



1. Example of the Class Anodonta and Unio 663 



2. Distinctive Characters and Classification 676 



Systematic Position of the Examples 678 



3. General Organisation 679 



Class II. Ampbineura 694 



1. Distinctive Characters and Classification 694 



2. General Organisation 695 



Class III. Gastropoda 702 



1. Example of the Class Triton rubicundus 702 



2. Distinctive Characters and Classification 713 



Systematic Position of the Example 715 



3. General Organisation 715 



Appendix to the Gastropoda 736 



Class IV. Scaphopoda 736 



Class V. Cephalopoda 738 



1. Examples of the Class ' 738 



i. Sepia 738 



ii. Nautilus pompilius ......... 754 



2. Distinctive Characters and Classification 766 



Systematic Position of the Examples 767 



3. General Organisation 768 



General Remarks on the Mollusca . 780 



INDEX . .... 783 



ZOOLOGY VOL. I. 



