37 



basalia-spicules protrudes. The lower end of this has been broken off but it is 

 still 12 mm. long. 



The macroscleres are essentially identical with those, of Hyalonema indicum. 

 Among the microscleres the dermal pinules, characterising as they do the species 

 by their peculiarities, are of particular interest. They are about 150 /« long. 

 The stout rays of their basal cross have an average length of 20 /-^ , terminate 

 bluntly, and are uniformly covered with short spines. The main ray is basally 

 5 /* thick, and smooth for a length of 20 /* . Its upper part is covered with 

 stout spines 20 /* long, which diverge considerably below but are nearly parallel, 

 closely " anliegend " above. The upper end consists of a stout central cone 

 8-12 M thick (pi. rv, f. 24). 



Macramphidiscs are rather rare. They attain a length of 200 /^ and a maximum 

 breadth of 70 /^ . Their terminal discs are bell-shaped, up to 80 /" lono-, and 

 have 8 pretty broad, spade-like marginal teeth. The shaft is fairly stout. It 

 has in the centre four crosswise arranged and, besides these, several irregularly 

 scattered, vertically diverging, blunt spines (pi. IV, f. 17). Much more minute 

 amphidiscs of similar shape, which are to be considered as mesamphidiscs (pi. IV, 

 f. 18), occur in small numbers. Micramphidiscs showing the usual characters are 

 plentiful (pi. IV, f. 19, 20). 



Micro-oxyhexactines are very numerous in the parenchyme. Their rays are 

 of medium thickness, about 60 /^ long and mostly distinctly rough or even tuber- 

 culous ; in some of them however the roughness is so slight that one might 

 almost consider them as smooth (pi. IV, f. 22). 



In the vicinity of the lower end of the body we find, just underneath the 

 surface, together with the stout acanthophores of the usual form, hexactines, 

 pentactines and cross-shaped tetractines with thin rays of different length (80- 

 200 /* ), covered with slender, vertically or obliquely diverging, straight or curved 

 spines, variable in size (pi. IV, f. 23). Ambuncinates were not met with. 



Of the Hyalonema species hitherto described, Hyalonema poculum F. B. Sch. 

 (" Challenger " Report, p. 208, pi. XXXIII) appears to be the one most closely 

 allied to H. weltneri. It differs from it, however, in the greater length and smaller 

 breadth of the dermal pinules. 



The only specimen of Hyalonema weltneri procured was captured in the 

 Laccadives 11' 12' 47" N., 74° 25' 5" E. in a depth of 1830 m.^1000 fths. 



I must finally mention that there are in the " Investigator " collection, be- 

 sides the Hyalonemas dcbcribed above, four isolated Hyalonema-root-tufts, 16-30 

 cm. long. These consist of loose bundles composed of 10-40 slightly spirally ' 

 twisted spicules which are in some up to 1 mm. thick. No remains of the body 

 of the sponges to which they belonged aic atLjiched to them. They are not 



