Cocconeis, Cymbella, Amphora and Amphiphora. 9 



Fig. 8. The line of deduplication becoming sulcated and two other lines 

 appearing one on each side. 



Fig. 9. Deduplication effected. 



Fig. 10. Lateral view of sporangial frustule. 



Fig. 11. Inferior view of sporangial frustule without endochrome, -^\-^ of 

 an inch long. 



Fig. 12. Oblique view of sporangial frustule after second or third dedupli- 

 cation. Lower individual. 



Fig. 13. Cymhella Pediculus (Kg.). Conjugating frustules relatively mag- 

 nified. The largest -g^-^ of an inch long. 



Fig. 14. Union of ditto in secreted mucus; endochromes elliptical, parallel 

 with frustules. 



Fig. 15. First appearance of sporangial frustules. 



Fig. 16. Transverse section showing the relative position of conjugating 

 and sporangial frustules at this period. 



Fig. 17. More advanced stage. 



Fig. 18. Ditto, where the valves of the conjugating frustules have become 

 divided. In this, as well as in figs. 15 & 17, one sporangial frus- 

 tule is hid behind the other, as explained by fig. 16. 



Fig. 19. Fully-formed sporangial frustules. 



Fig. 20. Sporangial frustule after Uberation from the sporangial mucus, &c., 

 ■3^-g of an inch long. 



Fig. 21. Amphora ovalis (Kg.), mihi. Conjugating frustules relatively mag- 

 nified. The larger -jrV^ oi an inch long. 



Fig. 22. Conjugating frustules approximated. 



Fig. 23. Ditto disunited, but held together by mucus, in which is seen 

 their endochrome divided into two spherical masses. 



Fig. 24. Sporangial frustules appearing, and elongating transversely to 

 the conjugating frustules. 



Fig. 25. Ditto in a more advanced state, valves of conjugating frustules 

 separating. 



Fig. 26. Ditto with ditto, more separated. 



Fig. 27. Sporangial frustules formed; two valves of the conjugating frus- 

 tules remaining in the centre, and one at each end. 



Fig. 28. Sporangial frustule liberated, ^-^o of ^^ ii^ch long. 



Fig. 29. Ditto undergoing deduplication. 



Fig. 30. Ditto after having undergone one or two deduplications, and again 

 about to deduplicate. 



Fig. 31. Conjugating frustule about to deduplicate; here inserted for 

 comparison with fig. 30. 



Fig. 32. Supposed preliminary state to fig. 28 ; endochrome fissiparating. 



Fig. 33. Amphiphora alata (?) (Kg.) : shows the broad side of the frustule, 

 the form of the central cavity, and the shape of the endochrome, 

 with terminal and lateral foramina. 



Fig. 34. Ditto under contortion. 



Fig. 35. Oblique view without the endochrome, showing the two compo- 

 nent parts of the frustule. 



Fig. 36. Lateral view without endochrome, showing lateral aperture. 



Fig. 37. Different forms of lineolation occasionally seen on the surface. 



Fig. 38. DedupUcation ; complete separation of the individuals not 

 effected. 



