372 Dr. C. Semper on Hyalonema Schultzei and Eurete. 



XL VI. — On Hyalonema Schultzei and on Eurete. 

 By Dr. C. Semper*. 



Hyalonema Schultzei ^ S., has the size and form of Euplec- 

 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 

 Eujplectella. 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 

 Euj)lectella. 



The forms of the numerous separate siliceous bodies call to 

 mind those of Hyalonema Sieholdiij Gray, from Japan. At 

 the upper end of the sponge a new species oi jEga had settled 

 in an enlarged canal ; this species, widely differing from that 

 of Euplectella^ I have named ^ga hirsuta^ on account of its 

 hairy limbs. 



The genus Eurete 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 in these siliceous tubes is surpri- 



* Translated by Fran Anna Semper, from the Transactions of the Society 

 for Medical and Physical Sciences at Wiirzburg, 13th Session, .July 



18, 1868. 



