On Badijlocahjx pumiceus (Stutchhunj). By W. J. Sottas. 123 



Dactylocdlyx pumieeus (Stutchbury).* 



Outer surface. — The under or outer surface of this widely 

 expanded vasiforni sponge is folded into a number of ridges and 

 deep grooves, which radiate in an irregular sinuous fashion from 

 the base towards the edge of the vase, the ridges frequently 

 anastomosing laterally in their course, so as to circumscribe the 

 grooves, which thus seldom extend continuously for more than 

 2 inches in length, and never beyond 2^ inches. The greatest 

 depth attained by these channels is fl"- The exterior of the 

 ridges is marked by circular openings from which more or less 

 cylindrical tubes are continued inwards into the sponge at right 

 angles to its surface ; these tubes either open directly into the 

 excurrent canals which we shall mention presently, or more fre- 

 quently, after branching once or twice, lose themselves in the large 

 meshes of the skeletal network. 



On the inner surface of the cup a number of round holes occur, 

 each elongated a little in a radiate direction, looking obliquely 



Fig. 10.- — Spicule involved in siliceous material, which has failed to com- 

 pletely invest one ray. At the point where the ray has been k-ft bare it appears 

 to have been reabsorbed, so that its extremity is quite disconnected with the 

 centre of the spicule, x 50. 



Fig. 11. — An octahedral node of the young fibre, x 50. 



Fig. 12. — Dermal sexradiate spicule, x 50. 



Fig. l.S. — Sexi'adiate spicule from the interior of the body skeleton, very 

 similar in size and form to those which furnished the framework of the secondary 

 network in Fig. 7, PI. VIII. X 50. 



Fig. 14. — Dermal sexradiate spicule, x 50. 



Fig. 15. — Dermal sexradiate with distal rays pointed and horizontal rays 

 capitate, x 50. 



Fig. 16. — Dermal sexradiate with the distal ray reduced to a capitate ter- 

 mination, x 50. a, distal ray on a larger scale. X 100. 



Fig. 17. — Sexradiate spicule with very long shaft, probably so disposed in the 

 sponge that the horizontal rays projected some distance beyond the dermal sur- 

 face. X 50. 



Fig. 18. — Curved small form of acerate spicule, capitate at both ends, x 50. 



Fig. 19. — Two flesh spicules cemented on to the skeletal fibre. 



Plate VIII. 



Fig. 1. — Young fibres oi D. pumiceus, showing their position relative to the 

 dermal spicules. X 100. 



Fig. 2. — Dermal layer of D. pumiceus, with the acerate spicules omitted. The 

 young fibres are represented in their relative position beneath it. 



Fig. 3. — Young fibre of D. pumiceus. x 100. 



Fig. 4. — A part of tiie network from the base of B. Stutchhuryi. x 50. 



Fig. 5. — A single mesh of the basal network filled in with secondary fibres. 

 X50. 



Fig. 6. — Young fibres of D. pumiceus. x 100. 



Fig. 7. — Secondary reticulation of "darning" fibres from D. pumiceus. x 50. 



* Stutchbury, 'Proc. Zool. Soc.,' 1841, pt. ix. p. SQ\ 'Ann. and Mag. Nat. 

 Hist.,' vol. ix. p. 504. Bowerbank, 'Proc. Zool. Soc.,' 18()!), p. 77, pi. iii. fig. 1. 

 Carter, ' Ann. and Mag. of Nat. Hist.,' ser. 4, vol. xii. p. 363. 



