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



them as primary ; and it is owing to this character, as well as to the body being per- 

 meated by a regular system of internal canals, that I must ^ place the form in question 

 as a new species in the genus Hvppospongia, F. E. Schulze. 



Colour. — Soft parts yellowish-pale, skeletal fibres dark yellow. 



Habitat— OS A^i, New Hebrides, 18th August, 1874 ; depth 60 to 70 fathoms. 



Cacospongia, Oscar Schmidt. 



Spongicte with readily distinguishable primary and secondary skeletal fibres of 

 comparatively thick diameter and forming comparatively large meshes. 



Cacospongia levis, n. sp. (PL V. figs. 1-3). 



The external surface of the single Challenger specimen is quite smooth except in 

 some spots where is is rather roughened by the ascending primary fibres. It is in this 

 property that, bearing in mind the conjectural afiinities of the species, I am inclined to 

 see its most important systematic character. The species seems to be closely allied to 

 Cacospongia mollior, but as we learn from F. E. Schidze (compare his ch'a^\ang in the 

 memoir on the Spongidte), the outer surface of the latter is denticulated throughout. 

 Again, the meshes of Cacospongia levis are rather smaller than those of Cacospongia 

 mollior, and its primary fibres are O'OB mm., the secondary ones only 0"04 mm. thick, 

 the corresponding fibres in Cacospongia mollior being on an average 0"15 mm. and 0"05 

 mm. in diameter. Approaching as regards these latter characters to my Hippospongia 

 anomala, the species in question difi"ers both from it and from JEuspongia officinalis var. 

 lobosa in a sharply pronounced rigidity of its skeleton. Just as in Hippospongia anomala, 

 the body of my Cacospongia levis proved also to be perforated by numerous canals, but 

 neither do these canals show, on the whole, any regular arrangement, being C[uite analogous 

 to those of Cacospongia cavernosa, nor is any membrane to be found above their terminal 

 points, so that there can be no doubt as to the systematic position of this sponge. The 

 primary fibres though not prominent may still be readily distinguished (PI. V. fig. 2). 

 They proved to be cored with foreign bodies, chiefly fragments of spicules lying, however, 

 only in the central part of the fibre ; in contrast to this, the secondary fibres are quite 

 devoid of any enclosures. In the soft parts of the specimen in question I found some forma- 

 tions which though lying free in the parenchyma, i.e., not surrounded by a special endothe- 

 lial layer, nevertheless presented a great resemblance to sperm-balls. A more careful 

 examination and the application of high magnifying powers showed, however, that these 

 formations are scarcely identical with sperm-baUs. Their contents consist of numerous 

 oval bodies in which no nucleus could be distinguished, but quite homogeneous throughout 



' Comp. p. 84. 



