548 REVISION OP THE AXINELLID^, ii., 



parts of the sponge, including the dermal membrane, hut are 

 nowhere extremely abundant: witliin the funes they ai-e, rather 

 scarce. 8ingly scattered trichites in moderate number also 

 occur, hut are difficult to perceive owing to their extreme tenuity. 

 The dragmata are unusually slender, and are often notably longer 

 than the individual trichites composing them. 



]\fpya)idpres. — (i.) The styli composing the fibres are almost 

 invariably more or less curved, anfl are, without exception, 

 e\'enly roundetl at the hase and of uniform or nearly uniform 

 diameter therefrom to be3'ond the middle of theii- length, whence 

 they taper gradually to a sharp point. Their curvature, as a 

 rule, is slight to moderate, and most frequently is confined to tlie 

 basal moiety of the spicule, hut it varies in degree a ery consider- 

 al)ly, and when most pronounced is usually somewhat angulate. 

 Quite commonly in the case of the smaller specimen, nnich less 

 f ret[uently in the larger, the basal part of the shaft, at a \ariable 

 distance fi'om the extremity, is more or less sharply curved or 

 l)ent to one side; occasionally such spicules have the form of 

 rhabdostyli. In the latter, or typical specimen, a notable pro- 

 portion (numbering between 25 and 50 per cent, of the spicules) 

 exhibit a faint annular swelling close to the basal end, at a dis- 

 tance therefrom varying from 15 to about SO/t, — the distance 

 usually being greatest, and the annulation less distinct, in the 

 case of the longest spicules; in some of the shorter spicules, the 

 annular swelling is replaced by a slight basal inflation, the 

 spicule becoming a subtylostyle. In the case of the smaller 

 specimen, this peculiarity is exceedingly rare. In the typical 

 specimen, also, the spicules increase in stoutness towards the 

 base of the sponge, attaining in proximity to the stalk a maximum 

 diameter of 45/^.; whereas in the uppermost regions thereof, and 

 throughout all parts of the other specimen, their diameter is at 

 most 33 or 34//.. Their length is aI)out the same in both speci- 

 mens, — ranging from about 350/x (but seldom less tlian 400 or 

 450/x) to somewhat above 900/x. 



(ii.) The longer and slenderer styli, occurring only between the 

 fibres, and relatively few, ai-e generally sti'aight or (in comparison 



