496 " THETIS " SCIENTIFIC RESULTS. 



Megascleres : — (1) Short, straight, minutely spined styli ; size 

 0-6 to 0-8 by 0-008 to 0-01 mm. 



(2) Stout, straight or slightly curved smooth styli in the fibres ; 

 size 0-4 to 0-5 by 0018 to 002 mm, 



(3) Smooth, rarely curved cylindrical styli, the longer kind 

 chiefly dermal ; the shorter are sparingly scattered throughout 

 the sponge; size 0-2 to 0-32 hy 0-0( 45 to 0006 mm. 



Microscleres : — small isochelse ; these are found mostly near the 

 surface ; they occur in dense bundles or stringy fibres, and are 

 so densely packed that it is difficult to see their form, except in 

 the thin margins of the clusters ; size 0012 to O'OIS mm. 



CLATHRIA MULTIPORA, sp nov. 



(Plate xlv., fig. 23.) 



Station 36. 



Sponge arising from a well formed disc attachment, with a 

 short peduncle and a great number of cylindric or slightly com- 

 pressed branches ; the mode of branching is mostly dichotomous, 

 and anastomization is exhibited by nearly every branch. The 

 specimen figured attains a height of 337 mm. The peduncle 

 is about 15 mm. in diameter, and the branches vary from 5 to 

 10 mm. The surface generally is minutely hispid, and exhibits 

 a white dermal incrustation, a series of shallow and mostly trans- 

 verse grooves, as well as innumerable oscula in the shape of round 

 pores, which are scattered over the whole of the branches ; on 

 an average they are about 5 mm. in diameter, and from 1 to 3 

 mm. apart. 



Texture slightly resilient, but somewhat brittle ; colour greyish- 

 brown. 



The skeleton consists of a series of stout primary fibres, which 

 form a closely arranged axial column and give off at regular 

 intervals gracefully cur\ ed secondaries which terminate at the 

 surface in radiating tufts of spicules. The main fibres are from 

 0".05 to 0-1 in diameter ; they have an axial core of closely 

 arranged smooth styli, about six or more in a row. The secondary 

 fibres measure 0*05 mm., and are usually furnished with three or 

 four spicules in the axial line and a few distinct echinating styli. 

 The connecting fibres are mostly unispicular and correspond with 

 the length of the spicule. The mesh is more or less rectangular^ 

 and measures about 0'2 to 0'3 mm. 



Megascleres : — (1) Straight echinating styli, wit^h recurved 

 spines, especially in the upper third; size 0"1 by 0'06 mm. 



(2) Large smooth styli in the fibres ; size 0'3 by 0-016 mm. 



(3) Small dermal, smooth styli; size 0*25 by 0'0065 mm. 



