By'r. von LENDENFELD, PH.D. 509 



Theix' thickness varies from O'Ol to 002 mm. They are attached 

 to the primaries by a broad trumpet-shaped extended basis. 



II. EUSPONGIA CANALICULATA ELASTICA. 



The main fibres are slightly and gracefully curved and taper 

 more abruptly toward the end, than in the foregoing variety. 

 The main fibres have a smooth surface and measure O'l mm. in 

 diameter, they are a little closer together than in the foi-egoing 

 variety. They contain axial foreign bodies, which, however, are 

 not near so numerous as in Eusponyia canaliculata dura. These 

 foreign body are mostly sand-grains, measuring on an average 0-02 

 mm. The connecting fibres are difierentiated into primaries and 

 secundaries not so distinctly, however, as in the variety described 

 above. Particularly we find not so great a difierence in thickness. 



The primaries are on an average 0-4 mm. apart and form angles 

 at the joining points of the secundaries. They, therefore, do not 

 appear like graceful curves pendant between adjacent main fibres, 

 but i-ather as broken lines, composed of longer or shorter straight 

 portions which are joined at angles approaching 180° very closely. 

 They measure 0'028 mm. in thickness. Also here we find those 

 which extend between distant main fibres thicker than those which 

 join two more adjacent main fibres. 



The secundaries are rarely simple, mostly they ramify and 

 anastamose so as to form a regular network, the meshes of which 

 measure 0*3 mm. on an average. 



The thickness of the secundaries varies from O'OOS to 0-02.5 mm. 

 The very thin ones are rare. The intermediate ones predominate. 



As the primaries are bent at the joining points and the secun- 

 daries approacii the thickness of the primaries the difi"erentiation 

 between primaries and secundaries becomes indistinct. 



Particidarly this becomes apparent between main fibres, which 

 lie close to each other where the network is similar to thai of 

 the subgenus Irregularis, whereas between the more distant main 

 fibres the differentiation is clearly visible. 



