234 ON A NEW GENUS OF HEXACTINELLID SPONGIDA. 



Fig. 11. Another piece of the vitreous fibre., wherein a, b, two main longitudinal branches, are seen, by 

 degrees, to approach, and further on, at c, to unite, and ultimately, by coalescence, to con- 

 stitute but a single thickened fibre. The areas between the glassy fibre are charged with loosely 

 arranged scopuline and other flesh-spicula. Specimen also very considerably enlarged. 



Fig. 12. A couple of what may be compared to sprays of the terminal filaments of the stout glassy fibre, 

 greatly magnified. These, though compound branched, are characteristically pitchfork in 

 appearance, the free tips towards the right (corresponding in part to what is shown in fig. 9) 

 being those that, so to say, protrude through the veil latticework, and hold it in place even in 

 the dried condition of the skeleton. In some of the terminal single fibres the sexradiate con- 

 dition is marked, but the axial fibre, nevertheless, ends in a tapering point. Minute dermal 

 and flesh-spicula abound in this specimen. 



Fig. 13. One of the longer scopuline flesh-spicules whose shaft is microspined. 



Fig. 14. Another spicule of the same kind, with secondary or spinal arms, set at right angles to the long 

 axis of the shaft. 



Fig. 15. Scopuline spicule, with microspined shaft and head, bearing expanded arms. 



Fig. 16. Variety of the last, with secondary or spinal arms. 



Fig. 17. One of the large (subskelatal) acerate spined spicula. 



Fig. 18. Portion of same, still further enlarged, to demonstrate arrangement of the spines on its shaft. 



Fig. 19. A group of the smaller-sized acerate flesh-spicula. 



Fig. 20. A hexactinelhd spiculum, with short axial arms, all the arms being slightly roughened or 

 microspined. 



Fig. 21. Sketch of the point of junction of a sexradiate spicule, the four arms of which persist, but only 

 a rudiment of one of the axial arms is apparent in a central knob. 



Fig. 22. A couple of the circumferential younger sexradiate glassy fibre, the arms being unequal in 

 length, the longer ones tending to curvature. 



Fig. 23. A few of the dermal hexactinellid spicula, i. e. those composing the lattice-like veil. At a the 

 mode of union of the squares is displayed, and at b a single sexradiate spicule is shown, with 

 a rosette in position tipping the free extremity of the axial arm. 



Fig. 24. A highly magnified representation in perspective of one of the small rosettes of the fleshy, 

 dermal, rectangular meshwork. (See fig. 23 b for its position with respect to the free axial 

 arm of the sexradiate spicule.) 



Fig. 25. The larger kind of multiradiate rosette, sparsely met with among the debris of the sponge. 



Fig. 26. A foreshortened view, or from above, of the cap or head of one of the rays of the rosette, fig. 25. 



Fig. 27. A spicule of a minute kind, of which only one or two were observed among the loose substance 

 shaken off the Denclrospongia, 



All the figures of the spicula, from 13 to 27 inclusive, are enormously enlarged ; and the relative propor- 

 tions as to size of the different sorts have not been strictly adhered to, though in the main approximated. 

 For their accurate measurements &c. consult description in body of text. 



