PLATE 19. — Diatomaceae and Entomostraca. 



Figure 



1. Acroperus nanus. 



2. Acroperus harpce. 



3. Alteuiha depressa. a, first pair of legs. 



4. Alona reticulata. 



5. Alona quadrangularis. 



6. Anomalocera Patersonii, male. 



7. Anchorella uncinata. a, arms ; b, abdomen ; c, ovarian tubes. 



8. Berleleya fragilis. a, natural size ; b, portion of a branch containing frustules ; 



c, side view, d, front view of a single frustule. 



9. Biddulpha aurita. Frustules undergoing division : a, hoop of original frustule, 



to which two new halves (c) have been formed ; the hoop of the new frustules 

 is seen at b ; the hoop of the parent has separated from the two frustules d d, 

 which are perfectly formed, each with its new hoop. 



10. Encyonema prostratum. a, frustules contained in a gelatinous tube, side view ; 



b, front view ; c, separate frustules, side view. 



11. Rliaphidoglcea micans. a, natural size ; b, group of frustules ; c, single frustule, 



front view. 



12. Schizonema Dillivynnii. a, natural size ; b, filaments containing frustules ; c, 



front view, d, side view of frustule. 



13. Zygoceros rhombus, a, front view ; b, side view. 



14. Syncyclia salpa ; frustules immersed in a gelatinous mass. 



15. Homveodadia anglica. a, portion of the natural size ; 6, part of a filament con- 



taining two frustules ; c, front view, d, side view of a prepared frustule. 



16. Dichieia alvoides. a, natural size; b, portion of frond containing frustules; c, 



d, f, prepared frustules, front view ; e, side view. 



17. Frustulia saxonica ; frustules immersed in a gelatinous mass. 



18. Cymbosira Agardhii. a, united frustules ; b, front view, c, side view of pre- 



pared frustules. 



19. Sphenella vulgaris, a, front view ; b, side view. 



20. Spermatozoa of a Cypris. 



21. Cetochilas septentrionalis, dorsal view. 



22. Notodelphys ascidicola, female. 



23. Lepeophthirus pectoralis, female. 



24. Lerneonema spratta, female. 



25. Macrothrix laticoimis, female. 



26. Moina rectirostris, female. 



27. Sida crystallina. 



28. Nebalia bipes. 



29. Polyphemus pediculus. 



30. Evadne Nordmanni. 



31. Peracantha truncata. a, superior antenna. 



32. Pleuroxus trigonellus. 



33. Terpsinoe musica : front view, PI. 25. fig. 10. 



34. Podosira hormoides, front view. 



35. Tessella interrupta, front view. 



36. Nicothoe astaci. a, ovaries. 



37. Cythere lutea. Poison-gland, a, and urticating organ, b. 



