BY E. P. KALLMANN. 547 



(ii.)of numerous, highly plumose, usually branched, short second- 

 ary fibres, which proceed off from the former, apparently from all 

 sides thereof, and run upwards and gradually outwards to the 

 surface. Towards the margin of the sponge, the funes dissolve 

 ultimately into similar plumose fibres (PI. xxxvii., fig.3), and the 

 skeleton in this region accordingly is composed entirely of such 

 (PI. xxxvii., figs.l, 2); these fibres are composed of a compact 

 stout core (seldom less than 200/x and frequently surpassing 

 400//, in diameter) of longitudinally disposed spicules, cemented 

 together b}" a relatively somewhat small amount of spongin, and 

 of rather numerous, usually very obliquely (often nearly or quite 

 perpendicularly) directed, outwardly-projecting or "echinating"' 

 spicules of similar kind, the number of which is greatest towards 

 the outer extremities of the fibres. The echinating spicules of 

 immediately adjoining fibres usually intercross with one another, 

 and very often, where two fibres lie sufficiently close together, 

 tlie points of some of the spicules of each of them become 

 embedded in the spongin of the other; occasionally, one or a few 

 together of these connecting spicules become invested with a 

 sheath of spongin, and a connecting fibre is thus formed, but 

 such connections are comparatively rare. Megascleres scattered 

 between the fibres are relatively few, and in part are much longer 

 and slenderer than those forming the fibres. The funes are com- 

 posed each of a dense, irregular plexus of stout, mostly non- 

 plumose fibres with closely compacted spicules arranged usually 

 in a more or less disorderly fashion, and cemented by a relatively 

 small amount of spongin, which does not form an external 

 sheath; the outermost-lying spicules of the fibres, indeed, ai-e 

 usually almost or quite free from spongin. Towards the older 

 parts of the sponge, the meshes of the plexus tend to become 

 obliterated, and the skeleton has the appearance of consisting of 

 a confused mass of spicules. The formation of the plexus ap- 

 pears to be brought about by the continued addition of spicules 

 to, and also in between, the plumose fibres of the original 

 skeleton. 



Trichodragmata are scattered fairly plentifully through all 



