68 THE VOYAGE OF H.M.S. CHALLENGER. 



surface agree so closely with Hyatt's Carteriospongia radiata, var. dulsiana, that I have 

 but to refer the reader to the description above mentioned, and wish only to elucidate the 

 anatomical and histological characters of the internal organisation of this interesting 

 species. So far as these latter are concerned, some details have been already given 

 (pp. 17, 18), and it now remains to expose them coherently. Through the pores, incon- 

 spicuous to the naked eye and scattered on both surfaces of the animal, the water reaches, 

 as usual, more or less developed subdermal cavities ; but these latter, instead of ramifying 

 liy forming smaller and more numerous canals (as is the case in Aplysina and to a certain 

 degree also in Euspongia and other allied genera), in most cases communicate immediately 

 with the flagellated chambers ; the dendroid cliaracter of these ramifications is here cj^uite lost. 

 The flagellated chambers (all larger than those of true Spongidae, but still of hemisjaherical 

 shape) having received the water by means of numerous pores in their walls, expel it, not 

 by means of special canaliculi as is the case in the true Spongidse, but through a large 

 opening like that in the flagellated chambers of Spongelidse. The water having left the 

 flagellated chambers enters large exhalent lacunse of variable outline, and many of 

 these latter uniting together throw it out through the oscula — in the Challenger 

 specimens all on the internal surface ; in some funnel-shaped specimens in the British 

 Museum, on the contrary, all on the external surface. It is an interesting fact that when 

 the sponges are of a leaf-like form, the exhalent orifices are always more or less con- 

 centrated on one surface only. In lanthella they are indeed to be found on both 

 surfaces, but still their distribution is not equal — they are numerous on one surface, but 

 very scanty on the other. The properties of the internal organisation are thus rather 

 deviating from those of typical Spongidse ; again, as to the histological structure of 

 the form in question, it difi"ers also from that of true Spongida3, its ground-mass being 

 almost entirely devoid of granules in the neighbourhood of the flagellated chambers. To 

 the conjectural systematic significance of these differences many pages have already been 

 devoted ; we have nevertheless come to the conclusion that at last, provisionally, the 

 genus must be still grouped in the family Spongidae, owing to the presence of those 

 enigmatic " Strange " of cells which have been recently described by F. E. Schulze, and 

 which, in spite of a remark of this naturalist as to their entire absence in some individuals 

 of Euspongia or Cacospongia, I am yet inclined to regard as very characteristic of the 

 whole family. In all the Spongidse I have had the opportunity of examining I found 

 them, and if absent in one region of the body they are still to be found in other 2:)arts of it. 



One of the specimens examined proved to be full of sperm-balls, one of which in a 

 ripe state is represented on PI. Y. fig. 9. I was able to discern also the preceding stages 

 of their development, but I abstain from their description here, since I shall return to 

 the matter when describing the spermospores of Verongia. 



Colour. — Pale dirty yellowish. 



Habitat. — Off Wednesday Island, Cape Yox-k, September 8, 1874 ; shallow water. 



