158 N. Annandale : Notes on Freshwater sponges. [VOL. Il, 1908.] 



stout, smooth, amphioxous, bent in a wide arc or, not infre- 

 quently, at an angle. No true flesh spicules. Gemmule 

 spicules terminating above in a rounded, knobUke structure 

 and below in a relatively broad, flat rotule, which is very 

 deepl}" and irregularly indented round the edge when ma- 

 ture, the spicule having the form of a sharp pin with a round 

 head at an earlier stage of development; shaft of adult 

 spicules projecting slightly below the rotule, long, slender, 

 generally armed with a few stout conical spines, which stand 

 out at right angles to it. Gemmules numerous throughout the 

 sponge, spherical, provided with a short, straight foraminal 

 tubule, surrounded by one row of spicules, which are embedded 

 in a rather thin granular coat. 



Average length of skeleton spicule 

 ,, breadth of skeleton spicule 

 ,, length of gemmule spicule 

 ,, diameter of rotule 

 ,, diameter of gemmule 



. 0-316 



mm 



• 0-0135 



)5 



. 0-046 



J > 



. 0-0162 



> ) 



. 0-446 



J> 



