Sponges from South Australia. 211 



Dysidea fragilis and Dysidea Kirkii therefore are fibrous, and 

 all the fibre arenated ; while on microscopically examining 

 the fibre itself it will be found to represent the lowest degree 

 of it above mentioned, viz. that in which the fibre is com- 

 posed of foreign objects held together by the merest minimum 

 or film of keratine, and hence its delicate and fragile nature, 

 from which Johnston's designation "fragilis" was derived; 

 but still it \% fibre. 



However, leaving this subject for the present, Mr. Wilson's 

 specimens from the neighbourhood of Port Phillip Heads, 

 South Australia, have brought me acquainted with a still 

 lower form, viz. that in which there is absolutely no fibre, 

 but where the foreign material is diffused, and so far held 

 together by being imbedded in the delicate flakes of the 

 parenchymatous sarcode generally ; where, traversed by 

 branches of the excretory canal-systems, it thus forms the 

 skeletal or supporting structure of the sponge, and under this 

 condition may assume many different sponge-like forms, 

 which may distinctly vary according to the species or variety, 

 but at the same time are all developed out of the same kind 

 of structure and composition through the specific agency of' 

 the " spjonge-sarcode " in which the whole originates and which 

 in all cases throughout the class of Spongida determines both 

 the form and the composition of the sponge. 



For this group I would propose the term " llolopsamma" 

 under the following diagnosis, viz. : — 



Holopsamma, nov. gen. 



Char. Arenaceous sponges without fibre, whose compo- 

 sition consists of foreign microscopic objects (sand, fragments 

 of sponge-spicules, &c.) diffused in the flakes of the paren- 

 chymatous sarcode ; traversed by the canals of the excretory 

 system ; assuming a variety of sponge-like forms, perhaps 

 chiefly massive, in which respectively the surface may consist 

 of the pore dermal membrane under any of the forms above 

 mentioned, that is, simple, continuous, and smooth, or ren- 

 dered more or less uneven and interrupted by the presence 

 and projection of the sandy element above the common level. 



1. Holopsamma crassa, n. sp. 



Form of specimen massive, variable. Consistence hard, 

 heavy, gritty, friable. Colour, when fresh, " bright orange- 

 yellow," now light brown, varying with that of the sand of 



