LIST OF ILLUSTRATIONS xxxi 



FIG. PAGE 



558. Nymphon hispidum 674 



559. Pentastomum tsenioides 674 



560. Macrobiotus hufelandi 675 



561. Diagram to illustrate affinities of Arthropoda 678 



562. Anodonta cygnea 681 



563. ,, ,, interior of valve and animal removed from shell . 682 



564. ,, ,, section of shell and mantle 683 



565. ,, cygnea, animal after removal of mantle-lobe . . . 685 



566. ,, ,, dissection from left side . . . . . . 686 



567. ,, ,, structure of gills . . . . . . 687 



568. ,, ,, transverse sections 688 



569. ,, diagram of circulation . . . . - . . . . 690 



570. ,, statocyst 691 



571. ,, early embryo . 692 



572. ,, later embryos 692 



573. ,, advanced embryo . . . . . . . . . 693 



574. ,, metamorphosis . . . . 694 



575. Anatomy of Pecten . . . . .... . . . . 697 



576. Valves of Mya, Modiola, and Vulsella . . . . . . 698 



577. Cardium edule . . ... 698 



578. Venus gnidia . . . . . ,. . . . . . 699 



579. Scrobicularia piperata . . . . .... . . 699 



580. Solecurtus strigillatus . . . . . . . . . . 700 



581. Diagram of concrescence of mantle-lobes 700 



582. Requienia and Hippurites 701 



583. Teredo navalis 701 



584. Aspergillum . . . . . . . . . . . .702 



585. Mytilus edulis . . . . . . . . . . .... .702 



586. Nucula delphinodonta . 703 



587. Gills of Pelecypoda . 704 



588. Gill-filaments of Mytilus ......... 705 



589. Dissection of Poromya . . . 705 



590. Donax, enteric canal 706 



591. Nervous system and auditory organs of Nucula . . . . 707 



592. Eye of Pecten . . . 708 



593. Development of Ostrea . ' . . . .709 



594. Veliger of Ostrea ... .709 



595. Embryos of Cyclas " . . . . . . 710 



596. Diagram illustrating the mutual relationships of the Pelecypoda . 712 



597. Chsetoderma nitidulum 713 



598. Neomenia carinata ^ * --,.-< . . 714 



599. Chiton, spinosus, dorsal view . . . . . 714 



600. ,, ventral view . . . 714 



601. ,, valves of shell 715 



602. Chsetoderma nitidulum, longitudinal section 716 



603. Chiton, longitudinal section . . . . 717 



604. Nervous system of Amphineura 717 



605. Neomenia carinata, reproductive organs 718 



606. Chiton, nephridial and genital systems ...... 719 



