33 



club-shaped, thickened, lower termination of the spicule. They are curved up- 

 wards forming a sharp bow, spade-like, and destitute of axial canals. The axial 

 Canal of the shaft terminates a short distance above the rounded, hemispherical 

 lower end ; 6 /^ above its termination the rudiments of the axial canals of the 

 four atrophied transverse rays, which together form a rectangular cross with 

 arms 6 ^ long, arise from it (pi. II, f. 14). 



The dermal pinules are pretty uniform in character. They are about 80 /^ 

 high; their basal rays, which form a rectangular cross, are about 85 /* lono-, 

 gradually attenuated towards the pointed end, and slightly spined in their distal 

 part. The spines of the main ray diverge from it with angles less than 45' 

 and form a crown 30-40 /* broad, which is gradually attenuated towards its 

 upper, pointed end. The basal part of the main ray is for a distance of 20-30 /* 

 free from spines. Together with the comparatively great length of the slender 

 basal rays this gives to these pinules a quite peculiar appearance (pi. II, f . 6 and 7.). 



The macramphidiscs of the dermal membrane are 200-300 /* long and have 

 a bell-shaped terminal disc about 70 /* long and equally broad, with eight 

 marginal teeth. The shaft is 12 /^ thick and covered with scattered, small 

 protuberances ; in the centre it has four or eight stout rounded tubercles. When 

 there are four they are arranged crosswise (pi. II, f. 9). 



The micramphidiscs are numerous. They vary in length from 10-30 /^ and 

 in the breadth of their terminal discs, which are hemispherical and have 10-12 

 marginal teeth, from 5-10 ^ . The shaft is slender and usually covered with 

 irregularly scattered, low spines (pi. II, f. 10-12). 



The parenchymal micro-oxyhexactines are numerous. They have straight, 

 smooth rays 70-80 /* long, and very gradually attenuated towards their pointed 

 ends (pi. II, f. 8). 



All the four specimens of this species are evidently young forms and their 

 root-tufts are free from Palythoa. Of other Hyalonema species the most closely 

 allied to this one appears to be Hijalonema globus F. E. Sch., of which a specimen 

 was captured in the vicinity of the Banda Islands in a depth of 958 m.=523 fths. 

 by the " Challenger " expedition. By its distinctly spherical or globe-like shape 

 and by the absence of prostalia lateralia it certainly differs very considerably 

 from the turnip-like, spined Hijalonema aculeatum in external appearance, but it 

 is similar to it in the shape and size of the microscleres, particularly the dermal 

 pinules. But also in these various differences are met with : the dermal pinules 

 of Hyalonema globus have a short terminal cone, those of Hyalonema aculeatum 

 a pointed end, etc. An identity of the two species is therefore out of the 

 question. 



All the four specimens were found in the Andamans, near North Sentinel 

 Island, in a depth of 458 m.=250 fths. 

 5 



