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614 C O L L E C T IO N S P R O M T H E W E S T E E N I N D I A N O C E A N .
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Clathrias, except perhaps C. elegans, Vosmaer (habit unknown), and
C. (Dictgoeylindrus) anchorata, Carter. Tbe latter is only known
from small shapeless masses, and bas the skeleton-spicule stout,
smooth, and strongly curved; otberwise tbe spicular complement
is essentially the same. In tbe present species tbe two kinds of
anchorates appear to be distinct, the smaUer form being very
abundant, the larger, though evidently normally present, much less
common ; the occurrence of a larger and smaller anchorate in some
Esperia’, as pointed out by Carter (Ann. & Alag. N. H. 1882, ix.
pp. 298, 299), is an analogous circumstance.
36. Clathria mæandrina. ( P l a t e L III. f i g . I ; P l a t e LIV.
figs. h -h " .)
Sponge only known as an incrusting, widely-spreading mass,
consisting of a thin basal lamina not exceeding 1 miUim. in thickness,
from which arise vertically, at intervals of 1 to 3 millim., parallel-walled
ndges, or triangular masses, about -5 to 1-5 miUim. in diameter and
2 -4 miPim. in height, usually united laterally to form a series of
meandi-ine ridges, generally 2 -3 miUim. apart, at tbe surface of tbe
sponge. Surface of basal lamina very uneven under lens, honeycombed
with round openings -25 to -75 miUim. in diameter ; the
trabecula between tbe openings is hirsute witb projecting spicules ;
surface of vertical ridges uneven, densely hirsute witb projecting
spicules and skeleton-fibres, towards the base it bas a honeycombed
appearance simUar to tb at of the basal lamina. Consistence in spirit
slightly résistent, but soft, compressible, elastic. Colour in spirit
buff-yeUow.
Main skeleton—arrangement suhrectangular; fibre dense, pale
amber-yellow, echinated sparsely below surface of sponge by spicule
no. 2, set at right angles to fibre. Primary fibres approximately vertical
to surface, terminating on it in short horny points densely clothed
witb spicule no. 1, wbicb are directed outwards, parallel to the axis
of the fibre; diameter of fibre about -05 to -1 millim. ; cored witb
proper spicules, usuaUy biserially arranged, to a variable distance,
not exceeding -7 mjllim., below surface ; distance of fibres apart
about -17 to -35 millim. Secondary fibres uncored, •035--07 millim.
thick,placed at intervals of about -17 millim., approximately vertical
to primaries. Dermal skeleton composed of a ratber close rectangularly
meshed reticulation ; fibres about -04--07 millim. thick,
apparently covered in parts by a thick incrustation of foreign
bodies. Sarcode transparent, very pale yellow-brown.
Spicules (1) Acuate, or with slightly constricted base, either
smooth or witb tbe base minutely spined, moderately curved, tapering
gradually from base to sharp point ; size -023 by -Oil to -013 millim.
(echinating tbe apices of primary fibres). (2) Spined acuate, straight ;
a head slightly indicated by a subterminal neck, spines minute to
moderate-sized, placed at right angles to long axis ; size of spicule
•075 by -0063 millim. (echinating fibres of main skeleton). (3) Sub-
spimilate or acuate, smooth, almost straight, tapering graduaUy from
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S P O N G I I D A .
near centre to sbarp p o in ts; size -32 by -0063 millim. (in axis of
outer extremities of primary fibres, and loose in tbe meshes of tbe
skeleton). (4) Tricurvate acerate, smooth ; the curves bold; tapering
to sbarp points ; size -076 to -12 by -0032 millim. (in sarcode).
(5) Equianchorate, shuttle-shaped, shaft slender, slightly and gra-
dually curved, palms each about one third tbe total length of tbe
spicule ; length -025 millim.
Hab. Marie Louise Island, Amirante group, 17 fms.; bottom coral.
Tbe specimen on w h ic h /b is species is based coats continuously
for a distance of 100 miUim. (4 inches) most of tbe circumference
of a stem (probably algal) 3 millim. in thickness. Tbe surface
of Spongia vulpina, Lamarck, in tbe Museum at tbe Jardin des
Plantes,_ Paris, decidedly recalls tbis sponge; but tb a t species is
tall, stipitate, and arborescent, witb a superficial spicular incrustation,
and hence is rather referable to Rhaphidophl us than Clathria; it
seems to want tbe tricurvate acerate spicule of the present species.
One remarkable point about tbe species is tbe unusually great
proportion of horny matter to spicules in tbe fibres. Tbis is also
shown in Tenacia clathrata, Schmidt, of the AV. Indies, wbicb, besides
its clathrous habit, differs from tbis species mainly in the very coarse
horny fibre, the considerably superior dimensions of tbe smooth
acuates, and tbe ratber clumsy form of tbe spined echinating
spicules.
37. Acarnus ternatus.
See P a rt I., p. 453, of tbis Peport.
A young specimen. Tbe tricurvates are somewhat shorter,
thicker, and more strongly curved than in tbo Australian specimens.
Hab. He des Neufs, Amirante Islands, 15 fms.
ECHINONEMA, Carter.
Tbis genus was nominally established in 1875 (Ann. & Mag. N. H.
1875, xvi. p. 185), in Mr. Carter’s “ Notes Introductory to the'Study
and Classification of the Spongida,” by the insertion of tbo words
“ Echinonema typicum, C., MS.,” under tbe Group Pluriformia,
Family Ectyonida, of tbe Order Echinonemata; but its characters were
not made known until 1881 {op. cit. 1881, vii. pp. 378-380), wben
Mr. Carter somewhat briefly described two species under tbis name,
viz. E. typicum and E. anchoratum, without, however, giving any
definition of the genus. I bave been able to examine a considerable
number of the specimens tbus identified by Mr. Carter, and find
them to be nearly allied to Rhaphidophlus of Ehlers (Espersch.
Spong. pp. 19, 31) and to Clathria, Schmidt, having the same general
character of spiculation and arrangement of the skeleton as these
genera, bnt differing from Clathria in having a non-flbrous and
purely spicular cortical layer, composed of acuates or spinulates
with their points directed outwards, and while agreeing with
Rhaphidophlus in tbis point, differing from it in tbo possession (not
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