294 



DISCOVERY REPORTS 



ends of wisps ending just below ectosome ; little or no spongin ; megascleres subtylo- 

 styli, occasionally almost stylote, 0-165 by 0-003 mm.; microscleres blunt-ended toxa, 

 0-07 by 0-002 mm. 







Fig. 19. Arenochalina incrustans, sp.n. a, section at right angles to surface, 

 showing "nests" of toxa at centre, x 36; 6, subtylostyle, x 500; c, toxon, 

 X 500; d, base of subtylostyle, very much enlarged, to show relative size of 

 axial canal. 



Remarks. The species is evidently a degenerate Mycale but whether it represents a 

 species in which the spiculation has become permanently degenerate, or whether it is 

 an individual, with skeleton pathologically affected, of a species with more normal 

 spiculation, it is impossible to say. At all events, the major part of a megasclere consists 

 of the axial canal (Fig. 19 d). 



The toxa are not distributed evenly throughout the tissues, as is usual, but are found 

 in "nests" (Fig. 19 a). 



Genus Acanthorhabdus, Burton 

 Acanthorhabdus fragilis, Burton. 



A.fragilis, Burton, 1929, p. 432, pi. iv, fig. 2, text-fig. 5. 

 Occurrence. St. 170: Clarence Island, 342 m. 

 Distribution. Victoria Land. 



