BY E. F. f^ALLMAXX. 521 



Sigmaxinello accordingly comprises at present five species, as 

 follows : - 



S. ausfraliana Dendy. S. arborea Kirkpatiick(20), 



S. ckndroides Whitelegge. S. viminalis, sp.n. 

 S. ramosa Carter(4). 

 Whether S. arborea strictly belongs to the genus as above 

 defined is not quite certain, inasmuch as its megascleres are 

 stated by Kirkpatrick to be of three kinds, (i.) basally attenuated 

 styli, 800-1150 X 25-37/x; (ii.) strongyla, 700-800x25-30/^; and 

 (iii.) "rhaphide-like" oxea (very rare), 700-870x12-5//. The 

 probability is, however, that the strongyla are merely variants 

 of the styli and connected with them by intermediate forms: 

 while very possibly the oxea are of foreign origin. 



SlGMAXlNELLA AUSTRALIANA Dendy. 



(Pl.xxxiii., figs. 1-3; PI. xxxiv., fig.l.) 



1896. Sigmaxinella australiana Dendy(7), p. 240. 



Diagnosis.- Ramose, erect, stipitate ; with cylindrical or 

 slightly compressed, moderately slender, dichotomously dividing 

 branches, usually of medium length and more or less arborescently 

 outspread, but occasionally remaining much abbreviated and 

 partially coherent together proximally. In outward appearance 

 much resembling a Chalinine sponge. Surface even; non-hispid. 

 Oscula in the form of shallow stelliform depressions, scatteied 

 or serial along the branches. Dermal membrane thin and 

 delicate, aspiculous. Skeleton fairly regularly reticulate, more 

 or less condensed axially; formed of spicule-cored, non-plumose 

 main fibres, and wholly sponginous connecting fibres. Mega- 

 scleres : subcylindrical styli and oxea and forms intermediate 

 between, often irregularly pointed, and rather variable in size 

 in the same specimen; with a maximal size, in different speci 

 mens, of from 360 to 4 50// by 7 to 17/a. Microscleres : slender 

 sigmata of two sizes, respectively 16 to 20// and 45 to 50/<. in 

 maximal length; and trichites, almost exclusively in dragmata, 

 20 to 45// in length. 



Xqc. — Port Phillip; Maroubra Bay, near Port Jackson. 



Introdxictory.—Oi this species, there have been examined, for 



