466 REVISIOX OF THE AXINELLin^^ i., 



which attain a diameter of 4 or 5/x; the length does not exceed 

 17/x. Malformed individuals, such as are of frequent occurrence 

 in T. diyitatus and T. pusUdusus, are i-arely to be found. 



Trachycladus digitatus Lendenfeld, et varr. 



Gpucral diai/nosis. — Branches moderately short, cylindrical to 

 clavate, occasionally (abruptly) pointed, but never, so far as 

 known, gradually tapered. Surface even, smooth to faintly 

 granular. Oscula scattered irregularly over the entire surface, 

 or (in the var. clavatus) arranged, or tending to become arranged, 

 in two longitudinal rows on opposite sides of the branches. 

 Dermal membrane varying (in the different varieties) from 50 to 

 120/x in maximal thickness; with closely packed spirulae through- 

 out its entire thickness (except in the var. sfronyyiatus, in 

 which the spirula> are confined tt) a superficial layer). Dermal 

 pores dispersed singly, at a distance apart from one another 

 generally greater than their own diameter. Skeleton with 

 moderately dense axial fune of diameter greater or less than the 

 length of the radial fibres. Radial fibres directed at an angle of 

 between 30° and 60° degrees to the axial direction; varying (in 

 different varieties) from 50 to 90 /x in maximal stoutness; with 

 spongin x'arely sufficient in quantity to form a distinct ensheath- 

 ing layer external to the spicules. Megascleres — except in the 

 var. stronyylatus (in which strongyla are the more numerous) — 

 consisting chiefly or almost exclusively of sharp-pointed oxea; of 

 considerably greater maximum size and generally of more fusi- 

 form shape in the stalk of the sponge than in the branches; 

 maximal size in the stalk varying (in diffei^ent varieties) fi'om not 

 less than 350 x 10/i to 530 x 23 /x. 



Hab. — South-eastern coast of Australia. 



Trachycladus digitatus, typical form. 

 (Pl.xxii., figs.l, 2; Pl.xxiii., fig.l; Pl.xxvi., fig.2; Pl.xxvii., fig.l.) 



1887. Sjiirophm-a digitata; Lendenfeld(26), p.794. 



1888. Spiroj)horel1a digitata; Lendenfeld(27), p. 236. 

 1914. Trachycladus digitatus; Hallmann(13), p. 429. 

 Diaynosis. — Branches moderately slender (4 to 6 mm. in 



