Plate IV. 



Eupledella marshaUi Ij. 



Fig. 4. Gastral view of the wall. Sieve-plate at the upper end. Nat. size. 

 Fig. 5. Showing the bottom-plate. Photo, from a drawing. Nat. size. 

 Fig. 6. A young (22 mm. long), before the breaking through of parietal 



oscula. Nat. size. 

 Fig. 7. Skeleton of a young specimen (32 mm. long). Nat. size. 

 Fig. 8. A young specimen, 42 mm. long. Nat. size. 

 Fig. 9. A young specimen, 63 mm. long. Nat ciz». 

 Fig. 10. Floricome. 440 x . 



Figs. 11-13. Three stages in floricome development. 440 x. 

 Fig. 14, Terminal of the immature floricome shown in fig. 13. With in- 



ceptional teeth. 1000 x . 

 Fig. 15. Sieve-plates of Hwo young specimens (39 mm. & 48 mm. long) ; 



seen from above. 2 x . 

 Fig. 16. Dermalia of an average size. 300 x . 

 Fig. 17. Oxyhexaster. 400 x . 

 Fig. 18. Young oxyhexaster. 440 x . 

 Eig. 19. Portion of a graphiocome. 440 x . 



Fig. 20. Portion of a graphiocome after the los.-i of the terminals. 1000 x . 

 Fig. 21. Lophocome. 440 x . 

 Fig. 22. Space between the apopyles (op.) looked at from the excurrent s\dv. 



440 X . c.vi., connecting membrane betw. the apoj)yles. lu.ia., 



marginal membrane of the chamber- wall, ir., trabeculje. 

 Fig. 23. A portion of the dermal membrane. A trabecula exjianded into 



a film-like band. 1000 x . ir.n., trabecular nucleus, tli., an old 



thesocyte. 

 Fig. 24. Portion of a thesocytal mass, showing the develoi>ment of thesocytes 



from archaiocytes (seen on the left). From a section stained with 



borax-carmine. 440 x . 

 Fig. 2:"). Four thesocytes from above. 1000 x . 

 Fig. 26, Lower end of a basal anclioring spicule. l.'iO x. 

 Fig. 27. Oscularia in situ. Below, the oscular sdge. .50 X . 

 Fig. 28. Section through the wall. 2;") x . — ^y.c/., arclucoeyte congeries, vh.L, 



chamber-layer, cx.tr., external trabecular layer, in.tr., internal 



trabecular layer, os.jii., oscular membrane, ose, oscularia. 



