by r. von lendenfeld, ph.d. 525 



Rigidity. 



The skeletons of these sponges are very tender and soft, and can 

 be pressed between the leaves of a book like a flower. 



COLOUR. 



In spirits yellow, The skeleton has a brownish hue. 



Canal System. 



Seienka had only dry specimens, and I only saw some half 

 decayed ones picked up on the beach, so that I cannot give any 

 reliable account of the configuration of the canal system. 



Skeleton. (Plate 36, fig. 5.) 



The skeleton is very regulai*. It consists of main fibres 

 "which extend in a longitudinal dii-ection along the Oscular tube 

 which, in the shape of a hollow cylinder, takes up the centre of the 

 digitate processes. From time to time, these fibres emit branches, 

 which gracefully curve towards the surface, spreading like a 

 fountain, and terminating in the superficial skeleton. 



These main fibres are on an average 1 mm. apart and measure 

 0-04 mm. in thickness. They are filled with large sand-grains 

 averaging 0-008 mm., which are so abundant as to cause the 

 surface of the fibre to become very rough. The knobs are large 

 and high. 



In the interior of the sponge a very regular net-work of con- 

 necting fibres is met with. These are difierentiated into pri- 

 maries and secundaries. The former are simple, straight or 

 slightly curved, very rarely branched, and never bent at their 

 joining points with the secundaries. They are vertical to the 

 main fibres, and connect the approximate fibres. 



They are always free from foreign bodies and measure 0*015 mm. 

 in thickness. They are particularly far apart. The interval 

 averages 0'2 mm. 



These primaries are connected by the secundaries. The latter 

 are always straight, unbranched and simple, and generally more or 



