420 



REVISION OF THE MONAXONID SPONGES, 111. 



able proportion of them ex- 

 hibit no basal enlargement 

 at all. It is to be noted 

 that styli are unrepresented 

 among the spicules which 

 project from the surface, 

 while they comprise almost 

 all of those spicules above- 

 mentioned which are dis- 

 posed transversely to the 

 longitudinal direction. 



The oxea are curved fusi- 

 form spicules varying in 

 length from 430 to 1040 /x, 

 and in diameter from (seldom 

 less than) 7 up to 12 /x. At 

 a rough estimate, they num- 

 ber somewhere between one 

 and five per cent, of the 

 principal megascleres. 



{b)The acanthostyles, when 

 fully developed, are conical 

 spicules with recurved spines 

 (about 3 jx high), measuring 

 from 65/Ato 102/x in length, 

 and at their base 10 fx in 

 diameter exclusive of spines; 

 the spines are scattered uni- 

 formly and pretty closely 

 over the whole surface. A 

 considerable number of im- 

 mature acanthostyles also 

 occur — of only slightly lesser 

 length than the fully devel- 

 oped — which are usually pro- 

 vided with a slight basal 

 Fig.ll. — Raspailia gracilis, a, Principal knob and are more and more 

 spicules; styli, subtvlostvli, and scarce • , i • i • 



oxea. a',Basal ends of principal spicules, ^^l^^t^^y spmed m propor- 

 6,Acanthostyli. c, Auxiliary styli and tion as thev are slender, 

 oxea. •' 



