HYALONEMA (PRIONEMA) FIMBRIATUM. 



301 



Occasionally smaller micropentactines with straight rays are met. In a 

 spicule of this kind the rays measured were 4 n thick at the base, the apical ray 

 was 54 M long ; the laterals were 34 ^ long. 



Of amphidiscs several kinds can be distinguished : — A, large ones, with 

 medium anchors the teeth of which are smooth, and have straight or outwardly 

 curved, diverging ends; B, large, medium-sized, and small ones with slender 

 anchors, the teeth of which bear frill-like, fimbriate membranes on their margins 

 and have inwardly curved, convergent ends; and C, small ones with broad 

 anchors, the teeth of which appear smooth and have end-parts more or less 

 parallel to the shaft. 



I measured 202 amphidiscs. The frequency of the various lengths is repre- 

 sented in the following exponential graph (Fig. 15). 



Number 

 30^ 



25- 



20- 



Macramphidiscs 



Fimbriate amphidiscs. 



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Length of Amphidiscs (/u). 

 Fig. 1.5. — -Amphidiscs. 



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