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frond, though only curved somewhat to one side in the plane of
expansion, was in life decumbent, so th at the terminal branches
were then in contact with tho sea-hottom. The species differs from
li. australiensis in the branching and anastomosing habit and the
flattened knife-edged branches, and in having the longitudinally
arranged spicules not confined to the axis, but extendiug to the
cortex. From R . syringella, Schmidt, it also differs iu its growth
(though Schmidt meutious th at the branches of R . syringella, sometimes
unite) and in the absence of heads to the acuate spicules.
AXINELLIDÆ.
Axinellida, Carter, Ann. Mag. N. H. 1875, xvi. p. 133.
This family differs from tho Ectyonidæ in the much greater
importance of size of spicule as a factor of specific distinction. The
relations of tho two families, however, require readjustment on
more satisfactory bases than a t present.
90. Axinella echidnæa. ( P l a t e X L III. fig. a.)
? Spongia echidnæa, Lamar'tfljAun. Mus. Hist. Nat. xx. p. 448.
I t seems likely that this will prove to be Lamarck’s species.
That author refers (I. c.) to Seba (Thesaurus, iii. pi. xcix. fig. 7) in
illustration of his sponge. This figure has a strong resemblance to
the present species, but does not show the same tendeucy to lateral
junction between the branches, and has most of the latter somewhat
enlarged at the tips, whereas iu these specimens they usually, though
uot invariably, are either of about the same diameter throughout
or else taper to points. The dark reddish-hrown colour of these
specimens and the peculiar echinatiou of their surface by angular
wedge- or knife-shape processes about 2 to 4 millim. high, projecting
outwards and somewhat upwards, aro decidedly indicated in the
figure. In texture the specimens are tough, elastic, harsh to the
touch in the dry state; the surface-processes are flexible, almost
soft, in spirit. Iu structure it is a true Axinella, and thus does
not support Lamarck’s surmise th at it might he identical with
Spongia muricata oî Esper (Pallas, sp.), which is Tricentrium muri-
catum of Ehlers. The main skeleton exhibits the usual longitudinally
elongated meshes of loose spiculo-fibre, which in the stem is
composed in part of a transparent and almost colourless horny uniting
material, which seems to bo wanting in the surface-tufts ; distance
between longitudinal lines of axis '07 to -1 millim. Surface covered
with a fuscous-brown suhopaque pigment, which penetrates to a
slight distance below. Sarcode transparent, almost colourless, very
pale reddish brown. Spicules :—(1) Smooth, slightly curved acerate,
tapering gradually to sharp points, or more or less blunted at
one or both ends ; size -3 hy '0095 to -44 by •0127 millim. : these
SPONGIIDA. 463
forms compose the main bulk of the skeleton. (2) Long smooth
acuate, generally slightly curved, tapering gradually to a fine point ;
size about l ' l , b y '0127 millim.: forming p art of longitudinal
skeleton-lines of surface-tufts.
Hah. Thursday Island and Prince of Wales Channel, Torres
Straits, 4 -7 fms.
Distrihution. “ African coasts ? ” (Lamardc).
As pointed out in speaking of the characters of the ends of the
branches, this form shows considerable variability : as a rule the
specimens are chiefly branched in one plane (fau-like), but in two
specimens branches project from both faces, but they then tend to
form fan-shaped fronds parallel to the main frond. The largest
specimen measures 160 millim. ( 6 | inches) high by 160 millim.
wide ; the average maximum diameter of the distinct branches
(which are cylindrical or somewhat compressed), not th a t of the
broadest but obviously compound branches (which occur commonly),
is about 10-12 millim. Five specimens occurred.
91. Acanthella, sp.
Externally resembling Spongia carduus, Lamarck (Ann. Mus.
Hist. Xat. XX . p. 381). When guided by the description alone,
I had referred the present specimen to this species with more confidence
than usual ; but on mounting sections of the probable type
specimen at Paris, I saw th at it was a different species. The
poiuts iu which the description does not quite suit this form are
“ pédicule cyliudracé, très-dur,” tho stem having apparently been
flattish, and, though stiff, uot inflexible ; and “ couleur d’uu blauc
grisâtre,” whereas this (in, spirit) is flesh-colour. The ridges run
longitudinally up and down the sponge, and are 1 to 3 milhm. high,
and their free edge is beset with sharp (in spirit flexible) points at
intervals of one or two millimetres. Texture tough and flexible,
substance compact, surface between inequalities glabrous. I t is a
true Acanthella. The spiculation is as follows :—(1) Smooth acuate,
slightly curved, tapering gradually to sharp point, about -4 to -6
millim. hy -0095 millim. (2) Smooth undulating cylindrical with
rounded ends, length about -7 millim., diameter ju st '0063 millim.
The species differs from the Adriatic forms A. acuta and obtusa,
Schmidt, in the broad explánate form and in tho smaller size of
the spicules, the cylindrical being much shorter and thinner, the
acuate much shorter than in those species. The skeleton forms
a loose-fibred AxineUa-liFo network of spicules, imbedded in a
dense, transparent, almost colourless mass of caoutchouc-like consistency,
containing nucleoid bodies about -007 to -008 millim. in
diameter.
Hab. Prince of Wales Channel, Torres Straits, 7 fms.
A single specimen in spirit, 35 millim. ( I f inch) high by 29
millim. across.
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