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382 COLLECTIONS FROM MELANESIA.
fibres rounded-angled meshes, G4 to -21 millim. in diameter, between
tho primiiries, which are about -42 millim. apart. Skeleton-fibres
amber-yellow in colour, usually homogeneous in appearance throughout.
Primaries cored to some little distance from surface by a
usually single series of small foreign bodies ; secondaries uncored.
Surcode dull pale brown, suhtransparent. Texture of sponge in
spirit very tongh and elastic.
Hab. Alert Island, Torres Straits, 7 fms.
(Distribution. “ Australian Seas ” (Lamardc) ?]
HIPPOSPONGIA.
Sdndze, Zeitsch. wiss. Zool. xxxii. p. G14.
Under this head, owing to the sheet-like aggregation of the
skeleton-fibres on the different surfaces, and the large tubular cavities
formed by the excretory canals, I am for the present including
those Spongiida? with mseaudrine main excretory canals, as Caco-
sqwngia cavernosa, Esper, and Spongia intestinalis, Lamarck, as a
subdivision of the genus. Characters may, perhaps, in the future
be discovered in their soft parts to justify their separation from
th at genus. The following is a third species referable to this section
of Hippospongia.
5. Hippospongia derasa*. ( P l a t e XLI. fig. A.)
Sponge suhglobose ; surface and interior of skeleton honeycombed
by maeandering and branching excretory canals 2 to 3 millim. in
diameter a t the surface, opening into larger spaces at a short distance
within the sponge. Texture of sponge firm, hut elastic, in dry
s ta te ; colour huff, becoming ochrcous in parts.
Skeleton at surface between openings of canals smooth and compact,
as if pared by a knife ; walls of canals smooth. Primary fibres
simple, straight, either (1) cored and set at right angles to surface, but
not projecting beyond it, diameter, where not distended by foreign
bodies, -05 millim.; or (2) not cored by foreign bodies, set approximately
at right angles to cored primaries, diameter about '035
millim. Secondaries forming either suhrectangular or irregular
meshes between the p rimaries; diameter -018 to -022 millim.
Diameter of the ultimate meshes -07 to -14 millim.; distance between
primary fibres -18 millim. Fibre dense, homogeneous, elastic ;
colour pale amber-yellow.
Hah. "West Island, Torres Straits (washed up).
The single dry specimen is subhemispherical, and measures 60
millim. ( 2 | inches) in length by 35 millim. (1-| inch) in height.
The species is most nearly allied to H. (Sp>ongia) intestinalis, Lamarck,
but has the fibres ouly about two thirds the stoutness of
those of that species, and it is suhglobose instead of being elongated
and tubular. The texture of intestinalis is coarser and hafsher
than th at of this species, partly owing to the thickness of the fibres
* Berado, to rub down, in allusion to the smoothness and compact texture
of the surface.
SPONGIIDA. 383
and the greater number of cored primaries. Spongia cavernosa,
Esper, differs from both in having the surface between the canals
echinated with tufts.
Tho peculiarly smooth and unbroken character of the surface of
the skeleton between the openings of the excretory canals appears
to be due mainly to the remarkable modification of the usual position
of the uncored primary fibres, by which, instead of running parallel
to the cored primaries, and so meeting the general surface at right
angles and (as is usually the case) by a superficial projection, they
run approximately at right angles to the very scanty cored fibres,
and so parallel to the general surface of the sponge ; the very close
interstitial network further adds to its density and evenness of the
texture.
STELOSPONGUS.
Stelospongos, Schmidt, Atl. Geb. p, 29 ; Hyatt, Mem. Bost. Soc. ii
pt. 3, p . 528.
Polyfibro.spongiii, Boiverhank, P. Z. S. 1877, p. 459.
Stelospongia, F. E. Schulze, Zeitsch. wiss. Zool. xxxii. p. 613.
btellospongia, Marshall, Zeitsch. wiss. Zool. xxxv, pp. 90, 118.
I cannot see any sufficient reason for Marshall’s mode of writing
the name of this genus. The first part of the word appears to be
based on ar/ffir], a column, from the frequency with which Schmidt
alludes to the columns ( “ Säulen ”) formed by the main fibres of the
skeleton.
6. Stelospongus excavatus. ( P l a t e XXXIX. fig. A.)
A small spirit-specimen, obtained at Port Molle, Queensland, has
a head which arises from a short pedicel, is broad and semitruncate
above, and cup-like, being excavated on its upper surface by four
pits, the deepest occupying a great part of the thickness of the sponge ;
each pit contains a vent ; the vents vary in size from about -25 to 3
millim. The colour in spirit is greyish white (putty colour) ; the
dermis conceals all the skeleton but the ends of the primary fibres
which appear as low points over the whole of the outer surface
and ju st inside the margins of the pits.
The skeleton-lines measure about -38 millim. in diameter, the
individual fibres of primary lines from '018 to -028 millim. in
diameter, those of the large secondary lines -07 millim. Both the
secondary and primary fibres enclose more or less foreign matter,
which also occurs on tho outside of the primary fibres and dermis]
forming a kind of mosaic. Greatest height and breadth of thè
single specimen 31 and 25 millim. respectively. Several large nucleated
and iinsegmented ova are discernible in the tissues, scattered
or aggregated in groups of two or three ; the diameter of the largest
is a b o u t-06 millim.; one was also observed which had apparently
divided into four segments.
A fine dry specimen, 300 millim. in gross height by 95 in the maximum
diameter of the cup, provided with a slender pedicel 150 millim.
long, breaking up below into a number of long stringy rooting
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