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



in the two specimens by which the species is represented, admitting probably of a 

 tolerably good distinction of the form in question from Cacospongia sjnnifcra. It is 

 the appearance of the outer surface, which is here not spinous but provided with rounded 

 tubercles. How far this peculiarity permits the estabhshment of a new species is difficult 

 to say ; at any rate I see at the present time no other course open but to separate the 

 form in question by the establishment of a new species. 



Both the specimens proved to be full of filaments, here, however, with heads of a 

 rather different shape from that of the filament-heads in my Cacospongia spinifera, 

 being of a more roundish outline, and with an average diameter of 0'055 mm. One of the 

 specimens proved to be quite compact, the other, as in Cacospongia cavernosa, was pierced 

 by numerous large internal channels inhabited by Chsetopoda. 



Colour. — Outer surface greyish, parenchyma white, skeletal fibres pale yellow. 



Habitat. — Station 162, April 2, 1874, ofi"East MonccBur Island, Bass Strait; depth 

 38 fathoms, sand and shells. 



Cacospongia intermedia, n. sp. (PL VI. fig. 7). 



I have already taken occasion to mention (p. 27) this species as presenting to the classifier 

 many difficulties. The meshes formed by its skeletal fibres being rather large, and the fibres 

 themselves thick, the form must be referred to Cacospongia ; but the fibres are almost all 

 of the same diameter (0'35 mm.), and it is only in the prominences of the outer part of 

 the skeleton that an approximate distinction between primary and secondary fibres is possible. 

 This character recalls the Coscinoderma of Carter; on the other hand, the body of the sponge 

 is broken through by numerous canals, the character of the outer surface of the skeleton 

 is that of Hiiypospongifi, the distinction between primary and secondary fibres, as already 

 stated, is pronounced only in the tufts ; all this would justify the placing of this sponge 

 in the genus Hippospongia, provided that one could prove the importance of the char- 

 acters just mentioned to be greater than that of the skeletal fibres being thick and the 

 meshes formed by them large. So far as to the general position of the form in question. 

 Now it must be mentioned that apart from the thickness of the skeletal fibres and the 

 largeness of their meshes, the sponge recalls vividly Euspongia vermicidata. What 

 systematic place is to be assigned to it ? Of course merely a provisional one, and accord- 

 ingly the task of the classifier is reduced to giving a detailed description of it. 



The species is represented in the collection by a single specimen of irregularl)- 

 massive form ; the outer surface is smooth and even, the dermal membrane enveloping 

 the skeleton with its external outgrowths in the same manner as in Hippospongia anomala. 

 In many spots the dermal membrane is pierced by larger or smaller (2 to 4 mm.) openings, 

 sometimes disposed by threes or fours together, sometimes lying isolated ; whether some 

 of these openings are really oscula is difficult to say without a complete destruction of 



