Ms :■
1. ■ Í* i
ii t
COLLECTIONS FROM MELANESIA.
Main skeleton strictly rectan g u lar; primary fibres -28 to -35
millim. apart at surface, secondaries -24 to -28 millim.; primaries
•053 to '07 millim. in diameter, spicules 2- or 3-serial; secondaries
•035 to -07 millim. in diameter, spicules uniserial; horny matter
strong, pale amber-yellow, composing two thirds of the fibre
in the primary, and five sixths in the secondary fibres. Dermal
skeleton a strong, usually quadrangular network, tending to be
rectangular, of similar composition to the main skeleton ; between
itô meshes is intercalated a close angular network of finer and
paler uniserially spiculate fibre, •OIS to ^024 millim. in diameter, the
meshes "053 to -14 millim. in diameter. Sarcode pale umber-
brown, granular. Spicule shghtly bent, smooth acerate, tapering
gradually to sharp points from three or four diameters from ends ;
size •115 by ^007 millim.
Hab. Alert and West Islands, Torres Straits, 7
fms. ; bottom
sand.
Three good and some more or less fragmentary specimens in
spirit. The two largest are 120 and 115 millim. (4|- and 4 |
inches) in length. The largest is composed of two stems, apparently
of independent origin, but one of them attached to and united with
the other at two points by broad masses of common substance. The
species is nearly allied to C. suharmigera, and hardly differs at all
exteriorly from the smooth form of th at species except in its apparently
slight tendency to form branches, but has the spicules of
about twice the diameter, and much fewer in number in proportion
to the horny matter, and the network of the main skeleton closer.
I t resembles Chalina montagui, Bowerbank (? Fleming) (Great
Britain), in tho general form and the size and shape of the spicules ;
but the fibre in th a t sjjecies is less horny and stout, and has but one
or two series of spicules.
I t is a curious fact th at at one of the points of union between the
two stems, as above described, a vent, originally belonging to one of
the stems, seems to have come into communication with the canal-
system of the other stem.
Cladochalina nuda, var. ahruptispicula. ( P l a t e XLI. f ig ./)
Bepent?, with single series of vents on one surface about 2 millim.
in diameter, from 15 millim. and upwards apart, margins level
with surface. Stem 8 to 12 millim. in diameter, slightly compressed,
unhranched ; surface even. Colour, in dry state, brown. Texture
tough, elastic. Main skeleton rectangular. Libre strong, pale
amber-yellow ; primary fibres about ^088 millim. thick, spicules
axial, about 3-serial, -35 to -5 millim. apart, with a margin of
horny matter ; secondary fibres, as primaries, hnt -044 to '088 millim.
thick, spicules somewhat loosely aggregated, 1- to 3-serial. Dermal
skeleton as in the typical form, but with stouter main fibres.
Sarcode pale yellow-brown, transparent. Spicules smooth acerate,
straight or almost so, coming abruptly to sharp ])oints within 1 |
diameter from ends : size 107 by -0063 millim.
Hab. Thursday Island, Torres Straits.
The abrupt termination of the spicules and the stouter fibre distinguish
this form of O. nucla. A single dry specimen, 105 millim.
(41 inches) long.
25. Cladochaliua suharmigera.
( P l a t e XXXIX. fig. H ; P l a t e XLI. figs. I, I'.)
Bepent, tortuous, solid, subcylindrical; stems 4 to 8 millim. in
diameter (2^ to 4 in a dwarf form), branching dichotomously at
rather long intervals, somewhat fiattened above. Branches of same
general character as stems, often increasing somewhat in diameter
towards apices, maximum length about 45 millim., attached at
various points of lower surface. A few sharp points 1 to 2 millim.
long project from sides of stem and branches here and there, especially
iu the neighbourhood of the larger vents ; absent in some
specimens ; surface otherwise even. Vents numerous, in a single
series, 2 to 6 millim. apart, along upper surfaces of stem*and
branches, circular, 1 to 2 millim. deep, 1 to 2-5 millim. in diameter;
lumen cylindrical; margins level with the flattened upper surface
of tho sponge. Texture in spirit compressible, elastic, to u g h ;
surface somewhat harsh to the to u ch ; colour umber-brown.
Main skeleton strictly rectangular in arrangement, rather variable
in size of meshes and diameter of fibres in different specimens ;
thus the distance between primaries is -28 to -77 millim., between
secondaries -042 to -28 millim.; diameter of primaries -053 to -09
millim., of secondaries -035 to -053 millim. (in dwarf form, primaries
-035 to -053, secondaries -023 to -035 millim.) ; fibre almost
entirely spicular, a very narrow horny margin alone being usually
discernible (rarely iu the dwarf specimen) ; spicules 6- to polyserial
in primaries, 3- to 5-serial in secondaries (in the dwarf form,
4- to 8-serial in the former, 2- to 4- in the latter). Dermal skeleton
of irregular wide meshes, composed of fibres of the same structure
as those of the main skeleton ; between these a close angular network
of fine unispicular fibre, meshes -053 to -08 millim. in diameter.
Horny matter of fibres amber-yellow. Sarcode rich yellowish brown,
finely granular. Spicules smooth acerate, slender, almost cylindrical
to within three diameters of ends, whence they taper to sharp points ;
size -08 by -0032 millim., -09 by -0032, -095 by -002, to -12 by
•002 (in different specimens).
Hab. Warrior Beef, Alert Island, Thursday Island, Prince of
Wales Channel, Torres Straits, 4 -7 fms., &c.; bottom pearl-shells
or sand, &c. Albany Island, N. coast of Australia, 3 -4 fm s.; bottom
mud (dwarf form).
A few spirit-specimens represent the larger form of the species,
one of them is 105 millim, ( 4 | inches) in maximum extent. A small
specimen, 25 millim. long, is the dwarf form above mentioned.
The species is perhaps most closely allied to Cladochalina armigera,
Duch. & Mich., of described .species ; the surface-spines, however]
which are the most striking external feature of G. armigera, are