130 Mr. J, S, Bowerbank on the Structure of Sponges. 



brought home from the Swan River, ALUStralia, by that inde- 

 fatigable naturalist Mr. Gould, preserved in spirit immediately 

 after it was taken from the sea. It is a young specimen of a 

 well-known Australian species, of which I have several spe- 

 cimens, and is represented of its natural size at fig. 1. PI. III. 

 It is elevated on a short foot- stalk, which, like the body of the 

 sponge, is of a compressed form. In the specimen figui'ed, 

 the greatest breadth of the body of the sponge is but little 

 more than equal to its height ; but in the other specimens in 

 my possession it has attained a much greater height, and in 

 one case rather exceeds thirteen inches, including the foot- 

 stalk, which is about two inches long. The height of the body 

 in this adult specimen is to the breadth as three to one. 



When removed from the spirit, the sponge has a dense, 

 opake and fleshy appearance, and feels weighty and solid to 

 the touch. Upon taking some very thin slices from about the 

 centre of one of the broadest surfaces of the sponge, and ex- 

 amining them with a power of 120 linear as transparent ob- 

 jects, they presented a highly interesting view of the struc- 

 ture. The horny fibre of the sj^onge, agreeing exactly in ap- 

 pearance with that of the specimens in my own possession, was 

 seen ramifying in every direction in the form of an amber- 

 coloured network, the interstices of which were filled up with 

 a fleshy substance veiy similar to that which occurs in such 

 abundance in the freshwater Spongilla and in many other si- 

 milarly constructed marine sponges, which are inhabitants of 

 the seas of the western and northern coasts of England ; and 

 throughout the whole of this fleshy structure siliceous spicula 

 were dispersed in great abundance, as represented in fig. 2. 

 Plate III. 



In Spongilla and in the marine sponges of Dr. Fleming's 

 genus Halichondria, the spicula are united systematically into 

 bundles so as to form a framework or skeleton, upon which 

 the softer parts of the animal are supported ; but in this Au- 

 stralian species they do not appear to assume any definite ar- 

 rangement, but are dispersed in all directions through the 

 substance of this cellular or fleshy part of the animal. The 

 spicula are ti'ansparent and hollow, like those of HcdicJiondria, 

 but vary extremely both in size and form. Some of them ter- 

 minate by a regular bifurcation, fig. 3. Plate III., and thus as- 

 sume the character of the triradiate calcareous spicula of Dr. 

 Fleming's genus Ch^antia ; while in others the bifurcated ter- 

 minations recurve and assume the form of an anchor with 

 short flukes, without palms, as represented in fig. 4. Plate III. ; 

 others assume very much the appearance of the prevailing 

 form of spiculum that is to be seen in many species of Ila/i- 



