8P0NGIIDA. 403 



and Australian specimens have rather thicker branches than those 

 from the Straits of M'alacca, viz. 12 to 2o millim. as against about 

 10 millim. 



J/iib. Prince of Wales Channel and Thursday Island, Torres 

 Straits, beach and 7—9 fms. ; Port Darwin, 7-12 fins. 



Distribution. Straits of Malacca (Bowerbank) ; New Guinea 

 (JBowerbank coll.). 



33. Toxochalina robusta. (Plate XXXIX. fig. G ; 

 Plate XLI. figs, n, n .) 



Repent, branching, attached usually by the lower surface of the 

 main stem or branches. Stem and branches subcylindrical, uneven 

 in places, subnodular, varying in diameter within short distances; 

 solid, not tubular. Branches given oft' at intervals of 1 to 2 

 inches, at angles of from about 30° to 80°, sometimes anastomosing. 

 Stem and main branches usually 10 to 18 millim. in greatest 

 diameter, some small branches descend to 4 and 5 millim. Vents 

 few, approximately one to the space between each two branches, 

 the margins usually sharp and projecting somewhat ; diameter 

 3 to 6 millim. ; excretory canals penetrating straight and deeply 

 into the substance of the sponge. Sponge, in spirit, tough, but 

 yielding and pliable (almost as much so as Chalina oculata, Pallas). 

 Internal fibres soft and elastic, forming a close network. Dermal 

 membrane firmer, parchment-like, even, glabrous, slightly marked 

 by the apices of the primary skeleton-fibres and the dermal skeleton- 

 network. Colour of sponge in spirit pale brown, inclined to yellow. 

 Main skeleton consisting of straight, stout, bright amber-yellow, 

 horny primary fibres, '05 to -075 millim. thick, and about -5 to *7 

 millim. apart at surface, meeting the surface at right angles, and 

 sometimes projecting slightly ; their apices are, however, connected 

 by a system of fine horizontal fibre-network ; spicules closely aggre- 

 gated, confined to the axis of fibre, forming a band there of about 

 6 to 8 spicules broad, and occupying, near the surface of the sponge, 

 only about one third of the total thickness of the fibre. Secondary 

 fibres at right angles to primaries, of paler yellow horny fibre, about 

 •035 to '05 millim. in diameter and "28 to "35 millim. apart; 

 spicules of axis in a unispicular series (occasionally two spicules 

 broad), often interrupted altogether or wholly wanting. Dermal 

 skeleton formed by a few very stout, dark yellow fibres, *05 to *1 

 millim. thick and 1 to 1*4 millim. apart, enclosing angular spaces 

 filled by a close subrectangular network of paler, mostly non-spicu- 

 late fibres from '009 to *045 millim. in diameter. Sarcode very pale 

 yellow, transparent, with numerous small dark granules. 



Skeleton- spicule acerate, tapering abruptly from within about \h 

 diameters of ends to very sharp points ; size "1 by -0032 to "0042 

 millim. Plesh-spicule tricurvate acerate, curves moderately bold, 

 tapering gradually to sharp points from centre ; size *05 to - 063 by 

 •0017 to -0021 millim. ; found in superficial and deeper parts of the 

 sponge, fairly abundant. 



Hah. Port Jackson, 0-5 fms. 



2d2 



