LIST OF ILLUSTRATIONS xxxi 



FIG. PAGE 



561. Anatomy of dipneumonous Spider 653 



562. Limulus, sagittal section 654 



563. Book-lung of spider 654 



564. Tracheal system of Spider 655 



565. Book-giU of Limulus 655 



566. Lateral eye of Euscorpio 655 



,567. Central eye of Euscorpio 656 



568. Nymphon hispidum 657 



569. Pentastomum taenioides 658 



570. Macrobiotus hufelandi 658 



571. Diagram to illustrate affinities of Arthropoda 661 



572. Anodonta cygnea 664 



573. ,. ,. interior of valve and animal removed from shell. 665 



574. ,, ,. section of shell and mantle 666 



575. .. ,, animal after removal of mantle-lobe . . . 667 



576. .. ,. dissection from left side 668 



577. ,. ., structure of gills 669 



578. ,, ,, transverse sections 670 



579. .. diagram of circulation 672 



580. .. statocyst . .673 



581. .. early embryo 674 



582. M later embryos 675 



583. ., advanced embryo 675 



.584. ,, metamorphosis 676 



585. Anatomy of Pecten 679 



586. Valves of Mya, Modiola, and Vulsella 680 



587. Cardium edule 680 



588. Venus gnidia 681 



589. Scrobicularia piperata 681 



590. Solecurtus strigillatus 682 



591. Diagram of concrescence of mantle -lobes 682 



592. Requienia and Hippurites 683 



593. Teredo navalis . . . .683 



594. Aspergillum 684 



595. Mytilus edulis 684 



596. Nucula delphinodonta 684 



597. Gills of Pelecypoda 685 



598. Gill-filaments of Mytilus 686 



599. Dissection of Poromya 686 



600. Donax, enteric canal 687 



601. Nervous system and auditory organs of Nucula .... 688 



602. Eye of Pecten 689 



603. Development of Ostrea . . . 690 



604. Veliger of Ostrea . 691 



605. Embryos of Cyclas 691 



606. Diagram illustrating the mutual relationships of the Pelecypoda. 693 



607. Chsetoderma nitidulum 695 



608. Neomenia carinata . 695 



