PLATE 19. DiatomaceaB and Entomostraca. 



Figure 



1. Acroperus nanus. 



2. Acroperus harpce. 



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



4. Alona reticulata. 



5. Alona quadrangularis. 



6. Anomalocera Patersonii, male. 



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



8. Berkeleya fragilis. a, natural size ; 6, portion of a branch containing frustules ; 



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



9. Biddulpha aurita. Prustules undergoing division : #, 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 ; 



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



11. Rhaphidoglcea micans. a, natural size ; 6, group of frustules ; c, single frustule, 



front view. 



12. Schizonema Dillwynnii. a, natural size ; >, filaments containing frustules ; c, 



front view, cZ, side view of frustule. 



13. Zygoceros rhombus, a, front view ; 6, side view. 



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



15. Homceocladia 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. Dickieia alvoides. a, natural size ; 6, portion of frond containing frustules ; c, 



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



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



18. Gymbosira Agardhii. a, united frustules ; 6, front view, c, side view of pre- 



pared frustules. 



19. Sphenella vulgaris. a, front view ; 6, side view. 



20. Spermatozoa of a Cypris. 



21. Cetochilus septentrionalis, dorsal view. 



22. Notodelpliys ascidicola, female. 



23. Lepeophthirus pectorcdis, female. 



24. Lerneonema spratta, female. 



25. Macrothrioc laticornis, female. 



26. Moina rectirostris t 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. 



