xxviii LIST OF ILLUSTRATIONS 



TIG. i'; u; J- 



520. Nymphon hispidum 025 



521. Pentastomum t<enioides 62;> 



522. Macrobiotus hufelandi 626 



523. Diagram to illustrate affinities of Arthropoda .... 



524. Anodonta cygnea 632 



525. ,, ,, interior of valve and animal removed from shell. (53:> 



526. .. section of shell and mantle 034 



527. , . cygnea, animal after removal of mantle-lobe . . . 636 



528. ,. ,, dissection from left side 637 



529. , , , , structure of gills . .... . . . 638 



530. ,, ,, transverse sections 631) 



531. ,, diagram of circulation 641 



532. ,, otocyst 642 



533. , , early embryo 643 



534. ,, later embryos 643 



535. ,, advanced embryo 644 



536 ,, metamorphosis 645 



537. Anatomy of Pecten 648 



538. Valves of Mya, Modiola, and Vulsella 649 



539. Cardium edule - . . . . 649 



540. Venus gnidia 650 



541. Scrobicularia piperata 650 



542. Solecurtus strigillatus 651 



543. Diagram of concrescence of mantle-lobes 651 



544. Requienia and Hippurites 652 



545. Teredo navalis . . . .652 



546. Aspergillum 653 



547. Mytilus edulis 653 



548. Nucula nucleus 654 



549. Gills of Pelecypoda . 655 



550. Gill-filaments of Mytilus 656 



551. Dissection of Poromya (556 



552. Donax, enteric canal 657 



553. Diagram of Nucula 657 



554. Nervous system and auditory organs of Nucula 658 



555. Eye of Pecten 659 



556. Development of Ostrea 660 



557. Veliger of Ostrea 060 



558. Embryos of Cyclas 601 



55<J. Ding-nun illustrating the mutual relationships of the Pelecypoda . 662 



560. Cheetoderma nitidulum 6(54 



r>6l. BTeomenia carinata 6(54 



562. Chiton spinoeus, dorsal view . . . 665 



56:5. ,, ventral view 6(55 



564. ,, valves of shell (565 



5(5."j. Ohfietoderma nitidiiluni, longitudinal section (5(5(5 



5(5(5. Chiton, longitudinal section (5(57 



567. Nervous system of Amphineura 667 



568. Neomenia carinata, reproductive organs 668 



