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and the fibre appears to agree with Ehlers’s account of the species,
hut I do not find the acuate spicules mentioned by him as occurring
less ahuudantly than the acerates ; the size of the latter in the present
specimens is -lo to '16 by ‘OOoS to -007 millim. (Ehlers gives
•17 millim. for the length) ; and I find (what Ehlers does not mention)
fine bihamates measuring -02 bj" ‘OOl to 'OOlfi millim. Eut a more
extraordinary fact connected with the species is th at the sponge-
tissue is almost entirely replaced (this seems to bo tho true explanation
of the facts) by a ramifying and anastomosing algal fibre,
•1 to 'IS millim in diameter, of a semitransparent appearance and
tough elastic texture in the dry state, like th at of dry isinglass : the
component cells are about -007 millim. in their smallest diameter.
I t appears to he the same species as th a t which forms the substratum
of the mass described by Bowerbank (P. Z. S. 1876, p. 771,
pi. Ixxx.) as Oplditaspongia fucoides, which is nothing more than
a coating Suheritid Sponge running over the fibrous filaments of
this same alga, which Bowerhank has taken, though not without
hesitation (see p. 772, I. c.) for the horny fibre of an Oplditi-
spongia, although he has identified isolated portions as alga. In
this case also it is not until examined with the microscope th at the
algal nature of most of the structure is identified with certainty.
This form of sjfmbiosis has been lately noticed by Prof. K. Semper
in ‘ Die natürlichen Existenz-Bedingungen’ (‘Animal Life,’ In te rnational
Scientific Series), where Sqjongia cartilaginea, Esper, is used
in illustration ; it is probably of not uncommon occurrence in the
Spongida. A Formosa specimen agrees closely in the characters
both of the sponge and alga with those from Australia. Mr. Carter
(Ann. &Mag. Nat. Hist. 1878, ii. p. 163) describes exactly the same
circumstance in an allied species from Hong Kong, and adds other
similar instances. Several specimens, dry and in spirit.
Hab. Thursday Island, Prince of Wales Channel, Torres Straits,
7 -9 fms. : Port Molle, Queensland, coral-reef.
Distrihution. Ceylon (Esper) ; Formosa (coll. Brit. AIus.).
This species has a similar habit to G. varius, if the form may he
regarded as th at of the sponge and not of the alga ; but its acerate
spicules are not so long and scarcely half as thick as those of that
species.
GELLIODES, g. n.
Desmacidinidæ of erect habit and well-defined form, fibre distinct
and compact ; outer surface of sponge beset with pointed eminences.
Spicules smooth skeleton acerate and bihamate.
This genus unites the habit of Echinonemata with the fibre of
Desmacidinidæ and the spiculation of Gellius (Desmacodes). Mr.
Carter (Ann. & Mag. N. H. 1882, ix. p. 288) has referred his species
Aæos fihulata to the genus Phorhas, Duch. and Mich., together
with his Axos ancliorata, which can hardly be generically identical
with it, as its spiculation is an acerate and an anchorate, while
Phorhas nmarantliv.s, the second species of the genus, has only an
acerate. Judging by the present specimens, A. fibulata wants also
the purple colour of Phorhas, on which Mr. Carter lays so much
w e ig h t; so th at I see nothing but the general external form by
which to connect this species with Phorhas, and this cannot suffice
for a point of affinity in the Spongiida.
62. Gelliodes fihulata.
(P late XXXIX. fig. I ; P late XLI. figs. hh-hh".)
? Spongia rubispina, Lamarck, Ann. AIus. Hist. Nat. xx. p. 450.
? Axos fibulata, Carter, Ann. 6f May. N. II. 1881, vii. p. 383, pi. xviii.
fig. 4.
Long cylindrical stems, given off from a common base, hut not
in a plane, irregularly curved, anastomosing a t points of contact,
aculeated at intervals of about 2 to 5 millim. by strong but slender
sharp spines 2 to 3 millim. long ; intermediate surface more or less
cavernous, ihe spaces more or less tympanized by membrane which
is semitransparent in spirit, transparent in the dried state. Skeleton-
fibre very compact, but exhibiting no horny material ; main fibres
going direct to surface, -18 to -28 millim. thick; secondaries given
off at various angles from primaries and at intervals of -43 millim.
and upwards, •088 to -18 millim. thick. Sarcode transparent, with
only the faintest tint of yellow. Spicules :—(1) Acerate, smooth,
tapering gradually to sharp points from near middle, slightly and
gradually curved ; size -25 by -0063 millim. ; forming the fibres.
(2) Bihamate, smooth, slender, with fine points, well curved ; size
•016 by -001 millim. Texture of sponge in dry state firm, very
harsh to touch, slightly flexible ; colour pale or darkish brown.
Ilah. Prince of Wales Channel and Thursday Island, Torres
Straits, 3 -10 fms. Abundant.
Distrihution. Bass’s Straits ( Carter) ?
Single branches attain a length of about 100 millim. (4 inches),
and the largest colony is 160 millim. (6 f inches) high. The species
differs from Lamarck’s description of S. rubispina in wanting the
white incrustation, and in not being branched in a fan-like manner;
it is doubtful what he means by an “ encroûtement coriace.” A
specimen in the Lamarckian collection named Spongia licheniformis
having apparently formed part of a turbinate or flattened mass,
even on one side and beset with low but sharp distant monticular
eminences on the other, has an almost identical spiculation, but the
fibres are less stout and are decidedly loose in their structure. I t
seems to me th at we have here a small natural assemblage of forms
representing a more primitive type of Desmacidinidæ than the forms
with anchorate spicules.
AMPHILECTUS.
Vosmaer, Family Desmacidinidce, Notes Roy. Mus. Netherl. ii. p. 109.
Although this genus as defined by Vosmaer appears to have
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