REPORT ON THE MONAXONIDA. 189 



very long, slender branches, but produced into a terminal portion which bears no 

 branches, and which itself extends further than any of them and is indistinguishable from 

 them excepting in being a direct continuation of the main stem. Length of sponge 

 (=that of the main stem) 475 mm.; diameter of stem and branches about 2 to 2*5 mm. 

 The branches are long, flexuous and string-like, and do not bear secondary branches. 

 Colour in spii-it greyish-yellow. Texture tough, string-like, with a coating of soft, friable 

 consistence. Surface roughened with minute monticular eminences like the surface of a 

 file ; hispid. Oscula minute, scattered. 



Skeleton. — There is a slender axial core of dense, amber-coloured horny matter 

 containing only a few slender spicules ; this core merges into a thick cylinder composed 

 of obliquely (sublongitudinally) arranged, closely placed spicules, which, when seen in 

 longitudinal section, present an irregular lattice-like arrangement, crossing one another at 

 acute angles. Transverse sections of the stem or branches show that there is also an 

 arrangement of stouter stylote spicules radiating from the central horny axis to the 

 circumference, beyond which they project like the spokes of a wheel. The skeleton is 

 much more strongly developed in the lower part of the stem than in the branches, and 

 a transverse section of this region bears under the microscope a most striking resemblance 

 to the flat bottom of a circular basket, the spicules representing the twigs of which it is 

 composed. In the branches the sheath of spicules surrounding the horny axis is much 

 thinner, and is covered with a thick coating of brownish-yellow, granular choanosome 

 containing the canal system and flagellated chaml^ers. We have already mentioned the 

 large, radiating stylote spicules which project beyond the surface of the sponge ; each of 

 these as it leaves the sponge is suiTounded by a faggot-like bunch of very small, slender 

 styU, which also have their apices projecting outwards. 



Spicules. — Megasclera ; (l) very long, smooth, slender styli (PI. XL. fig. 8); 

 straight, or nearly so ; usually, but not invariably, tapering very gradually to a very fine 

 point at the apex, size up to about 1'75 by 0"018 mm. (2) Smooth, slender strongyla 

 (PI. XL. fig. Sb), measuring up to about 0"77 by O'Ol mm. (3) Very slender, smooth 

 styli, surrounding the large ones as above mentioned, size about 0'42 by 0"0035 mm. (4) 

 Small, spined styli, of rare occurrence (very rare or absent except near the base of the 

 main stem), found radiately disposed, completely embedded in the densest parts of the 

 spicular skeleton ; spines rather large compared to the size of the spicule, short and 

 usually recurved towards its base ; size of spicule about 0"175 by 0'0125 mm. A few of 

 the slenderer amongst the smooth styli taper so much towards the base as to become 

 almost or sometimes quite oxeote (PI. XL. fig. 8a, h). 



This species comes very close to Bowerbank's Dictyocylindrus hispidus,^ but difi'ers 

 from it in its mode of branching and in the presence of the smooth, cylindrical spicules 

 (strongyla), which seem to replace the unequal-ended oxea found in the latter species. 



' Vide Mon. Brit. Spong., vol. iii. pi. xvii. 



