SILICIOUS AND HORNY SPONGES WILSON. 345 



Thiele, 1900 (p. 70), assigns sponges from Ternate to this species, 

 into which he would merge S. inconstans Dendy (Ceylon). 



Dendy, 19166 (p. 132), has recently reported the species, var. 

 tubulodigitata, from Okhamandal, and 19216 (p. 139) (type and 

 varieties) from the Indian Ocean. 



Vosmaer, 1911 (p. 14), merges in this species JS. digitata Hentschel, 

 from Southwest Australia. In S. digitata (Hentschel, 1909, p. 385), 

 the sponge body is massive with processes that are digitate, clavate, 

 lobular, or irregularly nodular ("knolliger Gestalt"). Megascleres 

 are subtylostyles varying toward the tylostyle and toward the style, 

 225-700 by 8-12 [x; there are two classes, large and small, but with 

 intergrades. Spirasters are 12-16 [/. long with stout irregular out- 

 growths which only rarely are spinous in shape. A cortex is not 

 mentioned, nor is the arrangement of the small megascleres stated. 

 The sponges are evidently close to the Albatross specimens. 



Vosmaer (1911) goes far in combining Spirastrella species. He 

 merges (p. 15) S. vagabunda, based on the study of Indo- Australian 

 sponges, in S. angulata Bowerbank, from Madeira, and this species 

 along with many others he combines under S. purpurea (Lamarck). 



Topsent, 19066 (p. 2), has redescribed the type specimens of S. 

 purpurea. The species is probably vasiform, one face (outer) bear- 

 ing radial tuberosities, the other (inner) without tuberosities and 

 with very numerous punctiform oscula about 1 mm. apart. There is 

 a " cortex " about 0.55 mm. thick ; at the surface, a crust of spirasters 

 and radial tylostyles, the points of which just project. Megascleres, 

 tylostyles 330-350 by 10-12 jjt,. Spirasters vary in size and details 

 of shape; the common large size, 22 \l long. 



Topsent, 1918, criticises Vosmaer's fusion of species as too ex- 

 tensive. Hentschel, 1912 (p. 324), and Stephens, 1915 (p. 434), 

 however, make use of S. purpurea in the extended sense of Vosmaer, 

 Hentschel recording under this name sponges from the Aru Islands, 

 while Stephens' sponges came from the South Atlantic. I incline 

 to believe with Topsent, 1918, that Vosmaer's species idea is too 

 comprehensive. In particular it seems to be that in the case of the 

 species here recorded (S. vagabunda), and in the case of many others, 

 some classificatory importance should be assigned to habits of growth 

 which, under suitable conditions, lead to the assumption of more 

 or less definite external characteristics. Such growth habits are 

 perhaps quite as hereditary as the small details of spicular shape 

 and size. 



With respect to the small radially placed megascleres at the surface 

 of the Albatross specimens, it must be supposed either that they are 

 of variable occurrence in the species (which would rob S. vagabunda 



