BY R. VON LENDENFELD, PH.D. 727 



The skeleton consists of a network of tine horny fibres, in the 

 axis of which spicules ac- are contained. These ai'e larger than in 

 most other species ; they are pretty numerous, straight, and 

 decidedly spindle-shaped, gradually pointed. 



Dactylochalinaaustralishas been found in Port Jackson (Ramsay, 

 V. Lendenfeld), Port Phillip (v. Lendenf eld), and Western Australia 

 (Baily). Among the numerous specimens of Dactylochalina 

 australis nova species examined by me, there were three which, 

 although similar in shape, could be distinguished from the others 

 by their greater rigidity. These came from Western Australia. 

 On microscopic investigation, it was found that these specimens 

 (dry) were not sponges at all, but Algae. The whole structure is 

 mainly formed of continually ramifying cylindrical branches, which 

 form occasional anastomoses, and terminate on the surface of the 

 digitate sponge with rounded ends. This structure is of a very 

 uniform nature throughout. The thickest stems and branches are 

 found in the interior ; they measure 0-15 mm. in diameter. The 

 final ramifications have a thickness of 0*08 mm. 



The meshes of the network formed by these threads, are about 

 0-5 mm. wide, and somewhat similar to the interstices between the 

 horny fibres in species of Dendrilla, but totally diflerent from the 

 shape of the meshes in the Chalinid sponges. 



The threads themselves are formed of the ordinary vegetable 

 cells, which are remarkable for their extremely thick wall. 



On burning portions of the specimens, and examining the ash, 

 the same spicules are found in great numbers, which are present in 

 Dactylochalina australis the sponge, whose shape this Alga so 

 closely resembles. 



In every detail the shape of the sponge is copied ; the protuber- 

 ances on the surface, and the oscula are there, but not a trace of 

 the horny skeleton of the sponge can be detected. 



In the specimens examined no spores were found, so that I am 

 not able to identify the Alga. It seems to be one of the Floridese. 

 There can be no doubt — this is proved by the presence of the silici- 



