482 ASTROSCLERA WILLEYANA, THE TYPE OF A XEW' FAMILY OF SPOXGES. 



Plate XL VI. 



Fig. 8. Part of a vertical section. ■• 105. The skeleton, formed of polyhedral elements, 



is coloured grey, and the soft tissue pink. The gelatinous layer of the upper surface is 



seen to contain scattered cells (c. j.) and spherules. It forms a thin membrane (m.), im- 

 perforate in the portion seen in this section, over the spaces connected with the openings of 



the canals. The beginning of the deeper-lying tissue with ciliated chambers (c. c/t.) is seen 



at the lower part of the figure. To the right an embryo is seen lying near the mouth of a 

 canal. 



Fig. 9. Section of an unsegmented egg showing the large nucleus (n.) and nucleolus. 

 X about 300. 



Fig. 10. Section of a .segmented embryo. The stained centres of the skeletal elements 

 are seen in the tracts of decalcified skeleton about it. x about 300. 



Plate XLVII. 



Fig. 11. Part of a vertical section showing a pore (p.) in the surface membrane, x 105. 



Fig. 12. Part of a vertical section through the interior, cutting two of the large 



canals (c.) longitudinallj-. x 105. Small canals given off from the large ones are seen to 



penetrate and divide in the tissues throughout which the ciliated chambers (c. ch.) are 

 scattered. 



Fig. 13. Part of a thick transverse section, showing the network of skeletal canals in 

 the interior, and the unperforated cortical layer {cort.) of the skeleton. 



Plate XLVIII. 



Fig. 14. Part of a thin transverse section through the soft tissue of the interior, from 

 a decalcified specimen. The skeleton has been filled in in a diagrammatic manner, x 170. 



Fig. 15. Part of a thin transverse section through the soft tissue of the interior, x 980. 

 The ciliated chambers are seen, with the flagellar processes projecting into them. Some larger 

 cells {I. c.) are scattered through the protoplasmic reticulum. 



Fig. 16 ct and b. Two ciliated chambers, x 980. In h a small canal is seen to be in 

 close proximity^ to the chamber. 



Fig. 17. Section showing communication between a ciliated chamber (c. ch.) and a small 

 canal (c'.). 



Figs. 18 and 19. Groups of scattered cells in the jelly near the upper surface. 



Fig. 20. Section through the soft tissue of a specimen whose canal system contains 

 masses of rod-shaped bodies {b.). x 250. 



