SPONGES. 173 



first branch 33 millims., diameter about 5 millims. Length of longest (lowest) 

 branch about 64 millims. ; greater transverse diameter of branches when fully 

 developed about 6 millims. 



The skeleton consists of a network of stout horny fibre, irregularly cored by smooth 

 megascleres and fairly abundantly echinated by spined styli. There is a well marked 

 axial condensation of the reticulation, in which most of the larger spicules are to be 

 found densely packed together lengthwise in the stout horny fibre. From this axial 

 portion more slender fibres run obliquely outwards to the surface, where each one ends 

 (typically) in a projecting brush composed of a very few long, stout styli, surrounded 

 at the base by numerous much shorter and very slender styli (these often appear to 

 be absent). The outwardly-directed horny fibres are irregularly cored by usually 

 slender megascleres and abundantly echinated towards their outer ends by spined 

 styli. They are connected together to form a network by short secondary fibres of 

 similar structure, but more slender. There are also many of the smooth megascleres 

 scattered through the soft tissues apparently without any relation to the fibres at all 



Spicules. (1.) Smooth styli (Plate XI., fig. 7, a); long and comparatively stout, 

 evenly rounded off at the base, gradually and sharply pointed at the apex ; usually 

 slightly curved towards the base; size about 0'65 millim. by 0'018 millim. ; found 

 chiefly in the axial condensation (but also scattered in the soft tissues outside it) and 

 in the surface brushes. 



(2.) Smooth styli (Plate XL, fig. 7, b, c) ; very slender, straight or nearly so, 

 evenly rounded off at the base and very finely and gradually pointed at the apex ; 

 size, say about 0'24 millim. by 0'0027 millim., but sometimes longer ; characteristic 

 of the surface brushes, but also occurring frequently between the axis and the surface ; 

 perhaps sometimes oxeote. 



(3.) Smooth oxea (Plate XL, fig. 7, d, e, f, g); rather short and fairly stout, 

 fusiform, more or less curved or angulated in the middle, gradually sharp pointed at 

 each end; size very variable, commonly about - 2 millim. by 0'012 millim., but may 

 be as much as 0'4G millim. by 0'014 millim. ; abundant, scattered irregularly outside 

 the horny fibres, and within them. 



(4.) Strongyla (Plate XL, fig. 7, h, h) ; very short and comparatively stout, straight, 

 equal-ended and broadly rounded off at each end ; size very variable, say alx>ut 

 0'2 millim. by 0'024 millim. ; sometimes pretty numerous in the axial condensation 

 and occasionally met with outside it, but very erratic in occurrence. 



(5.) Spined styli or sub-tylostyli (Plate XL, fig. 7, k, I, m) ; rather short, straight, 

 tapering gradually from base to apex, which, though narrow, is bluntly pointed ; 

 covered all over with very minute, sharp spines, which are most abundant at the base 

 and apex ; size about 0'08 millim. by O'OOS millim. (at the base, including spines). 



Numerous small, spherical, granular, brown pigment cells, about O'Ol millim. in 

 diameter, are scattered through the outer part of the soft tissues. 



This species, though evidently closely related to the European Raspailia (Dictyn- 



