394 ECHIVAXIA AND RHABDOSIGMA, 



axially condensed skeleton, and also differs from Echinaxia, 

 Axinectya, and Raspaxilla in the absence of megascleres corres- 

 ponding to the long (principal) styli, and from Raspaxilla^ 

 furthermore, in the non-possession of special dermal megascleres. 

 For the reception of this species, accordingly, a new genus 

 appears also to be required, and for this I propose the name 

 Heterectya. 



ECHINAXIA FRONDULA Whitelcgge. 



(Plate xxi., figs.3, 4; Plate xxii., figs. 1, 2; and Text-fig. 1). 

 1907. Axinella frondula Whitelegge, Mem. Austr. Mus.,iv., Pt. 



10, p.509, PI. xlvi., fig.32. 

 1916. Echinaxia frondula. Kallmann, Proc. Linn. Soc. N. S. 



Wales, xli., Pt. 3, p.543. 

 External features. — The single example of the species which 

 has so far been obtained consists of a very thin, flabelliform 

 lamina, gradually narrowed proximally into a (likewise much 

 compressed) stalk-like prolongation, and divided marginally, by 

 very wide and deep notches, into four sub-spathulate lobes. A 

 figure illustrating the external form accompanies the original 

 description. The specimen appears to be complete with the 

 exception of the basal extremity of the stalk; but possibly it 

 represents only portion of a much larger specimen, of very deeply 

 partite, or foliose, habit. It measures 75 mm. in total height, 

 50 mm. in greatest width, 7 mm. in width at the lower extremity 

 of the stalk, and only from 1 to IJ mm. in thickness (except 

 towards the base, where it ultimately attains a thickness slightly 

 exceeding 2 mm.). The surface is even, and presents a densely 

 hispid, or, rather, finely pilose appearance, due to the projection 

 beyond the dermal membrane of the terminal spicules of the 

 skeletal fibres; the dermal membrane, which is excessively thin, 

 is thereby rendered quite indistinct. Oscula are not discernible. 

 The consistency of the sponge in alcohol is moderately firm and 

 tough, flexible and elastic; the colour, light brownish-grey. 



Skeleton. — The skeleton (Plate xxii., figs.l, 2) consists (i.) of 

 a dense and sharply delimited axial region, of reticulate pattern, 

 composed chiefly or almost entirely of small, smooth styli, and 



