BY E. F. HALLMAXX. 469 



part of their course, run for ;i short distance close below the 

 dermal membrane, and, being visible through it, present an ap- 

 pearance as of veins radiating to the oscula. The colour (in 

 spirit) is a faintly yellowish pale grey witli the least possible 

 tinge of olive-green; at the same time, the sponge has a slightly 

 subtranslucent appearance, somewhat recalling that of wax. The 

 consistency is rather fleshy, moderately soft, yet fairly tough and 

 elastic; the branches stand firmly erect. 



The dermal pores are disposed in the manner shown in PI. 

 xxvi., fig.2, and PI. xxvii., fig.l. They vary from 30 to S5//. in 

 diameter, and number, on the average, between 60 and 70 per 

 sq. mm. 



Skdetun. — The skeleton, as seen in its entirety (PL xxiii., fig.l), 

 is of a hght greyish colour, tinted very faintly with brownish 

 pale yellow in the condensed axial region and in its older por- 

 tions. By reflected light alone, the axial condensation can barely 

 be perceived, being obscured fi'om view by the extra-axial 

 skeleton ; but with the opposite illumination, — as when the 

 skeleton is held directly between the eye and the light — it is 

 seen as a sharply delimited, apparently solid core, occupying 

 about one-fourth the diameter of the branches. The extra-axial 

 skeleton appears, at first sight, to consist solely of radially 

 directed fibres — 2 to 3 nnu. in length — which are inclined to the 

 forward direction of the axis at an angle varying from about 30" 

 in the distal region of the branches to about 45" in tlie basal; 

 but, on closer inspection, transverse fibres (very rare towards the 

 periphery of the skeleton, but becoming fairly numerous as the 

 axis is approached) connecting these can be made out. The 

 extra-axial skeleton is rather scanty — itt efi'ectiveness in conceal- 

 ing from view the axial condensation being due mainly to the 

 very oblique inclination of the radial fibres. 



The radial fibres are from 30 to 70/x (rarely more) in stout- 

 ness, and, speaking generally, consist almost entirely «f mega- 

 scleres regularly arranged in close parallelism, — the spongin 

 cementing the spicules seldom forming a very well defined 

 sheath, and more usually being so small in cpiantit as to be 



