10 Spong. 
XVII. SPONGLE. 
Roberts & Phillips (41) give a popular account of the structure 
of Sponges. 
Schulze (43) discusses the derivation of the eight-rayed spicules 
(Discoctaster) of certain Hexactinellida (some species of Acanthascus and 
Rhabdocalyptus ) from the Hexaster. In these spicules the eight rays 
arise quite regularly, corresponding to the eight angles of a cube ; the 
base* of the rays, in transverse section, is three-lobed ; between the bases 
of the rays, corresponding to the centres of the six sides of the cube, 
there are six prominences. On each of these six prominences are four 
ridges (standing at right angles to each other), which join on to the four 
neighbouring rays. Schulze propounds the theory that the six promi- 
nences correspond to the original chief rays of the Hexaster. Each of 
the original six rays became split into four (corresponding to the four 
ridges). These twenty-four split rays met in threes at points corres- 
ponding to the angles of a cube, then became fused, and thus eight rays 
were formed. 
Stedman (44) describes certain structures in Spongilla lacustris, which 
he thinks may correspond to a nervous system. Sectionized spirit- 
material showed spindle- or star- shaped cells, eudiug in thread-like 
processes, with granular protoplasm, and large and prominent nuclei. 
Topsent (52) gives an account of his examination of living Sponges. 
He found great differences in their relative consistency, which apparently 
depends on histological modifications. Some Sponges, such as Desma- 
cidon fruticosus , Dendoryx incrustans, D. reses, Reniera viscosa , on being 
taken out of the water, give off an abundance of a thread-like liquid, 
which is a true mucus, secreted by spherical cells of glandular nature, as 
can be shown by staining with aniline. Others, chiefly Reniera indi - 
stincta , are viscous. They possess spherical cells, which often serve, at 
the same time, as glands and as nutritive reservoirs. Finally, many of 
the Chalinince and Ectyonince are elastic. In them are found spherical 
cells which apparently have the function of connective tissue. 
Topsent (55) approves of Lendenfeld’s new generic name Tetranthella 
for Suberites fruticosus and L. crambe of O. Schmidt, as the generic 
name Crambe, proposed by Yosmaer, had been already applied by 
Linmeus to a cruciferous plant. Vosmaer is not right in his supposition 
that the few observed chelae belong to the Sponge. 
Yosmaer (61) gives a preliminary account of some Tetractinellida of 
the Bay of Naples, which had either been insufficiently described, or 
which vary to such an extent that a revision of their specific nomenr 
clature was necessary. According to Vosmaer, many species vary 
enormously, and those which, by most authors, are regarded as distinct 
species, should at the most be called “ varieties.” Thus he acknowledges 
only one species of Thenea (2\ muricata (Bwk.) Gray), which includes 
|he numerous species so carefully described by Sollas. 
Yosmaer (62), referring to Lendenfeld’s note (22), says that ho 
examined the type specimens of Suberites fruticosus and S. crambe , 0. S., 
so long as fourteen years ago, fouud them identical, and placed them 
