PAPERS READ. 



STUDIES ON SPONGES. 



(Plates 39-44.) 



By R. von Lendenpeld, Ph.D. 



1.— THE VESTIBULE OF DENDRILLA 

 CAVERNOSA. Nova Species. 



Among the Australian Sponges which belong to the genus 

 Dendrilla, there is one which is remarkable for the peculiar 

 laxity of its structure. The sponge is digitate and of a dull 

 yellowish coloui*. The skeletal fibres are dark brown to black. 

 The sponge does not change its colour like some related species 

 when exposed to the air. It attains a height of 400 mm., and the 

 very irregular digitate processes average a width of 25 mm. The 

 conuli on the outer surface are irregular, distant (average 8 mm.), 

 and 2 mm. -4 mm. high. 



Oscula are scattered over the surface. They are found on the 

 sides of the digitate processes, but never appear situated terminally- 

 The oscula are circular, 3 mm. in diameter. 



The whole sponge appears, as mentioned above, to be entirely 

 hollow, A large cylindrical cavity takes up the whole interior of 

 each digitate process. The processes themselves hereby attain a 

 tubular appearance. 



Below, in the central, irregular mass from which the processes 

 grow out, the cylindrical cavities of the digitate processes join 

 (fig. 1), to form an extensive cavity traversed here and there by 

 bridges of tissue. This whole cavity is a pseudogaster, no oscula 

 are found in its surface ; it is a vestibule belonging to the inhalent 

 system. 



