900 THE IIOMOCOELA DESCRIBED FROM AUSTRALIA, 



Skeleton : Two forms of spicules are to be distinguished, regular 

 and sagittal. 



The regular spicules possess slender rays, which are 018 mm. 

 long and 16-20 as long as thick, cylindrical with rounded end. 



The basal ray is sometimes rather longer than this, some 

 of them show an incipient fourth apical ray. 



The sagittal triradiate spicules are on an average of the same 

 size as the regular ; their rays, comjtared with those of the latter, 

 are more conical, although there is no want of intermediate stages, 

 they are not constant in their outline. With some of them the 

 irregularity consists only in their not being flat, the point of 

 meeting of the rays not lying in the same plane as their ends, the 

 basal ray being in this case either of the length of the lateral 

 rays or rather longer ; but such a form is comjjaratively rare. 

 The greater part also show variation in their angles ; the angle 

 formed by the basal, and each of the lateral rays varying from 

 120*^ to 92° ; the length of the basal ray is in this case variable 

 (0-12-0-25 mm.) ; it is either straight or undulating, the lateral 

 rays being horn-shaped and curved, more or less, one towards the 

 other. There exists also on the outer surface of the colony another 

 constituent part of the dermal skeleton, namely, large regular 

 triradiate spicules ; each ray attaining a length of -8 mm. and a 

 diameter of 0'06 mm ; but these spicules are so extremely rare 

 thai they are of no importance. 



Special description taken from Polejaeff (I.e.) where the Sponge 

 is figured. 



Colour : Yellowish. 



Locality: Australia. Station 186, September 8th, 1874, lat. 

 10^ 30' S., long. 142^ 18' E. ; Cape York, depth 8 fathoms. Coral 

 sand, Challenger. 



2. GENUS. ASCALTIS. Haeckel. 

 Asconidse, with triradiate and quadriradiate spicules. 



