372 Dr. C. Semper on Hyalonema Schultzei and Eurete. 
XLVI.—On Hyalonema Schultzei and on Eurete. 
By Dr. C. SEMPER*. 
Hvatonema Scuvrrzet, §., has the size and form of Huplec- 
tella aspergillum. 'The fibres of the roots, which are either 
smooth or toothed, divide themselves towards the body of the 
sponge into separate tufts, which spread in the interior as well 
as on the surface of the sponge itself, and here bear a similar 
relation to its framework as the fibres of the roots of the 
Euplectella, Cruciated spicula of very varied forms then 
unite with those longitudinal lines of fibres, thus forming a 
network of a more or less compact tissue, which is crossed in 
all directions by the large canals of the sponge. The com- 
paratively wide expirating oscula range irregularly around the 
whole sponge; near them are often tufts of fine silk-like 
fibres. In some parts of the somewhat injured surface there 
is a fine tissue forming wide rectangular meshes. The whole 
network of the sponge is formed, as is the case with all real 
species of Hyalonema, of unconnected fibres or cruciated spi- 
cula, though sometimes single spicula blend together, and thus 
point at the origin of the ‘connected siliceous network of the 
Euplectella. 
The forms of the numerous separate siliceous bodies call to 
mind those of Hyalonema Steboldii, Gray, from Japan. At 
the upper end of the sponge a new species of Aga had settled 
in an enlarged canal; this species, widely differmg from that 
of Euplectella, I have named Aiga hirsuta, on account of its 
hairy limbs. 
The genus Hurete was established on a coral-shaped sponge, 
the cylindrical and hollow branches of which grow together. 
The wide oscula at the extremities of its branches seem to be 
the expirating, the small holes between the network forming 
the lining of the tubes the inspirating orifices. The tissue of 
the lining of the tubes, being of about one millim. thickness, is 
formed of a rather compact net of fine siliceous tubes, which 
sometimes are blended irregularly, but sometimes cross each 
other very regularly, thus forming a network including rect- 
angular meshes. There do not appear to exist separate cruciated 
spicula; but frequently the cavities of the connected cruciated 
fibres remain independent of each other, so that often two or 
three adjoining though unconnected cavities are cemented by 
the common siliceous mass. The extraordinary size of the 
cavity of the central fibres im these siliceous tubes is surpri- 
* Translated by Frau Anna Semper, from the Transactions of the Society 
for Medical and Physical Sciences at Wiirzburg, 13th Session, July 
18, 1868. 
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