LIST OF ILLUSTRATIONS xxxi 



558. Nymphon hispiduni ... . 674 



559. Pentastomum tienioides 674 



560. Macrobiotus hufelandi 675 



561. Diagram to illustrate affinities of Arthropoda . 678 



562. Anodonta cygnea . . 681 



563. ,, „ interior of \ahe and animal removed from shell . 682 



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



565. ,, oygnea, animal after removal of mantle-lobo 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 

 •172. ,, later embryos . ... 692 



573. ,, advanced embryo . 693 



574. „ metamorpho.si."; 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-tilaments 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 ... . 7l4 



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 systen> of Amphineura 717 



605. Neomenia carinata, reproductive organs .... . 718 

 ^06. Chitop, nephridjal ^nd genital systefns . . 719 



