PLATE 111. 



PAGE 



Isolated spicules of Euplectella aspergUhmi, Owen, . . 64 



Fig. 1. Oxyhexaster from, the parenchyma of the side wall ; x 300. 



Figs. 2-10. Various endings of the rays of larger spicules ; x 100. 



Fig. 11. Floricome; x 300. 



Fig. 12. Triact from the side wall, with two long straight rays in one axis, and a shorter somewhat 



curved third ray. All the free extremities are thickened and spindle-shaped, and beset 



with teeth ; x 100. 

 Fig. 13. Oxypentact from the lateral wall, with a long, slightly curved radial, and four shorter 



tangential rays, disposed at right angles, and of equal length ; x 100. 

 Fig. 14. Compact hexact with two terminally club-shaped and rounded rays, and four becoming 



uniformly narrower to the truncated ends ; x 100. 

 Fig. 15. .Simple, regular, somewhat slender oxyhexact from the parenchyma of the side wall ; x 100. 

 Fig. 16. Hypodermal oxypentact with a much elongated and slightly curved proximal radial ray; 



xlOO. 

 Fig. 17. Pentact with rough pointed ends on aU the rays, of which four, lying in one plane, belong to 



two axes crossed at right angles, and are of equal length and straight, while the fifth ray 



is shorter, somewhat curved, and at right angles to the above-mentioned plane; x 100. 

 Fig. 18. Strongly developed regular hexact with somewhat truncated ends to the elongated conical 



rays ; x 100. 

 Fig. 19. Strongly developed triact in which the three elongated conical rays are terminally somewhat 



rounded off. Two rays lie in a straight line, while the third, which is somewhat thicker, 



stands at right angles. A trace of an undeveloped fourth ray is seen opposite the third, 



as a protuberance, into which a short rudimentary canal enters; x 100. 

 Fig. 20. Tetract with rough ends. Two long straight rays lie in the same axis. Two other, shorter 



but unequal, straight rays lie at right angles to one another and to the last ray ; x 100. 

 Fig. 21. Oxydiact with the somewhat curved rays in one axis. A spindle-shaped swelling in the 



middle exhibits four rudiments of canals, disposed at right angles, the last traces of the 



other four undeveloped rays ; x 100. 

 Fig. 22. Oxypentact of anchor form, with one very long ray and four shorter equal rays, with a marked 



hook-shaped curvature. From the upper portion of the root-tuft of a young specimen : 

 xlOO. 

 Fig. 23. Pentact of anchor form from the root-tuft. At the end of the long, smooth, straight principal 



there are four equal, short, hook-shaped anchor rays ; x 100. 



Fig. 24. Compact pentact in which one unpaired ray is thickened into a club at the end and 

 roughened, while the other four straight rays, at right angles to the above, lie in one 

 plane and have rounded ends ; x 100. 



Fig. 25. Triact with curved rays with rough ends, two of unequal length in one axis, with the third 

 and shortest at right angles ; x 100. 



Fig. 26. Triact with approximately equal and straight rays, two of which lie in the same axis ; x 100. 



Fig. 27. Compact tetract with four unequal rounded rays in one plane ; x 100. 



Fig. 28. Compact tetract in which two of the rays, lying in the same axis and in a straight line, are of 

 equal length and truncated, while of the two rays in the other cross axis, one is longer 

 and terminally truncated, while the fourth is much shorter and rounded off like a club ; 

 X 100. 



Fig. 29. An anchor needle from the basal root-tuft, representing a diact in which the two rays are in 

 one axis and straight, but beset with prosimally curved lateral teeth. While the one 

 proximal ray is very long and terminally pointed, the distal is short and ends in an 

 anchor-shaped expansion with eight recurved, paddle-shaped, anchor teeth. In this 

 anchor-shaped expansion the axial canal breaks up into a tuft of terminal canals. Some- 

 what above the inferior extremity is seen the axial intersection of the central canal, 

 representing the centre of the diact ; x 300. 



