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II. Hexactinellidse O, S,
Genus Hyalonema Gray
Hyalonema rosea n. sp.
Plate 23, fig. 1—11, Plate 26, fig. 5.
This new Hyalonema is represented by only three specimens,
which are very fine and well preserved, ali from the east coast
of Greenland. Ali the specimens are round or ratlxer
ellipti-cal and compressed, the form slightly agreeing with that of a
Polymastia Bow., the mamulse naturally excepted. The three
■examples are almost of the same size, one a little larger, the
greatest diameter 40 mm, the shortest not exceeding 25 mm.
The height is tolerably constant, only 5 mm. The surface is
even, but slightly hispid, the spicules being congregated in
irregular bundles and projecting from the surface. The lower
surface is a little concave. The distal margin obtusely
at-tenuated. Oscula are minute, numerous, and dispersed. The
consistencv of the sponge like that of tolerably firm felt.
Skeleton. The skeleton consists of large hexradiate
■spicules, only five of the rays being well developed; one of
the rays is much longer than the others; of smaller hexradiate,
ali the rays being well developed; of rosettes of one kind;
of slightly curved obtuse spicules with both the terminations
microspined, and the spicule not rarely infiated at the middle;
of very large acerate, sometimes spined along the points; of
small, spined acerate spicules with four inflations at the middle,
and finallv of more rare spinulate spicules, the heads of which
are microspined.
The large obtuse spicules (Plate 23, fig. 3—4). These spicules
are always more or less curved and armed with very minute
spines at both the terminations. They are very numerous and
often infiated at the middle. The length of such a spicule
does not exceed 10 mm.
Tlie large acerate spicules (Plate 23, fig. 1). The spicules of
this kind are the largest in this species. They are usually
totally smooth, but sometimes slightly spined at the points.
The central cavity is very large and seems to communicate
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