25G On Deep-sea Sponges from the Atlantic Ocean, dec. 



shaft ; /, falx or eighth arm of head joininfr the latter to the 

 shaft. 



Fig. 21. The same, bihamate flesh-spicule. 



Fig. 22. Cladorhiza abyssicola, Sara, inequiaiichorate of, to compare with 

 the foregoing : a, lateral view ; 6, dorsal view ; c c, aborted 

 ends ; d, alate appendages of shaft ; e, falx. 



The other flesh-spicule, viz. the bihamate, being of enormous 

 size, is too large to be here introduced. 



Fig. 23. Ifistodcnna appendiculatum, n. sp., natural size: a, body ; b, tu- 

 bular appendages ; c, conical projection at the end. 



Fi(]. 24. The same, equianchorate : a, lateral view ; b, anterior view. 



Fig. 2o. The same, bihamate flesh-spicule. 



Fig, 2l3. Halichondria abgssi, n. sp., natural size, on a deciduous ostra- 

 cean shell : a, sponge ; b, shell. 



Fig. 27. The same, equianchorate : a, anterior view ; b, lateral view ; 

 c, embryonic fonn. 



N.B. Here there are no alate appendages, but the end of the 

 shaft widens into the umbrella-like head. 



Fig. 28. The same, tricurvate flesh-spicule, seen in one of the two 

 specimens only. 



Fig. 29. Halichondria forcipis, Bk., upper surface, natural size : a, 

 fragment of dermal surface, to show pore-arese = cribriform sar- 

 code in the inter.stices of the skeleton-structure. 



Fig. 30. The same, lower surface, natural size : showing large can- 

 cellous structure, and detritus imbedded in the sarcode : a, 

 deciduous ostracean bivalve shell. 



Fig. .31. The same, equianchorate : a, lateral view ; b, anterior view. 



Fig. 32. The same, forcipiform spicule incipiently spined : a, full-grown 

 form ; b, embryonic form. 



Fig. 33. Cliona abyssorum, n. sp., spiro-sinuous flesh-spicule. 



Plate XV. 



All the spicules in this Plate are drawn on the scale of l-12th to 

 l-1800th of an inch, with the exception of figs. 42, a, 43, a, b, 44, a, and 

 4o, a, b,c, which are all on the scale of l-24th to 1-1 800th inch, and 

 fig. 47, on the scale of l-12thto 1-GOOOth inch, to show their relative sizes. 



Fig. 34. Guitarrajivibriata, skeleton-spicule of one form only. 



Fig. 35. Meloiianchura elliptica, skeleton-spicules of two forms : a, small ; 



b, larger form. 

 Fig. 36. Esperia villosa, skeleton-spicule of one form only. 

 F^g. 37. Fsperia cupressiformis, skeleton-spicule of one form only. 

 Fig. 38. Chondrocladia virgata, Wy. Thomson, skeleton-spicule of one 



form only. 

 Fig. 39. Ilidoderynn appendiculatum, skeleton-spicules of two forms : 



a, large ; b, smaller form. 

 Fig. 40. Halichondria abyssi, skeleton-spicules of three forms : a, long 



acerate ; b, shorter and stout acuate ; c, smallest, with inflated 



ends. 

 Fig. 41. Halichondria forcipis, Bk., skeleton-spicule of two forms : a, 



small ; b, large. 

 Fig. 42. Desmacella pumilio, Schmidt : a, skeleton-spicule of one form 



only ; b and c, flesh-spicules, tricurvate and bihamate respec- 

 tively. 

 Fig. 43. Dictyoeylindrus anchorata, n. sp. : a, skeleton-spicule of one kind 



