REPORT ON THE KERATOSA. 63 



the specimen ; but this is certain, that most of them are " pseudo-stomata," leading into 

 the canals separating the body of the sponge, and the envelope of whose walls is merely 

 the continued dermal membrane. The properties of the skeleton have been already 

 discussed, and I hope that with the help of the figure given on PL VI. its characters will 

 be rendered obvious ; its outer surface recalls that of Hiiypospongia mauritiana (PL VI. 

 fig. 3), apart from an entire absence of bundles of parallel fibres. 



Colour. — Outer surface black, parenchyma greyish, skeletal fibres brown. 



Habitat. — Station 177, ofi" Api, New Hebrides, August 18, 1874; depth 130 

 fathoms, volcanic mud. 



Cacospotigia irregularis, n. sp. (PL VI. fig. 10 ; PL VIII. fig. 5). 



The chief peculiarity of this curious species consists in this property of its skeleton, 

 that, in contrast to all other Spongidaj, the bundles of its fibres are so closely and 

 irregularly intertwined that the distinction of primary and secondary ones is entirely 

 impossible ; they form a kind of irregular network, its meshes being not represented by 

 internal channels as in HipposjJOf^gia, but filled by parenchyma. The species is repre- 

 sented in the collection by a single specimen, apparently of irregularly massive form, in 

 reality provided with large internal cavities, so that the sponge can be compared to a 

 casket. The surface is smooth, but not devoid here and there of outgrowths correspond- 

 ing to the prominent tufts of skeletal fibres, presenting a compact network, and in most 

 cases ending more or less shar23ly. As to the secondary meshes of the skeleton, they are 

 quite irregular, and my drawing (PL VI. fig. 10) will give a better explanation of them 

 than any words. The primary meshes, i.e., meshes formed by the skeletal fibres them- 

 selves, are in most cases small, but in others very large, and occasionally a mesh is repre- 

 sented by two bundles forming an acute or obtuse angle and a single usually thick fibre. 

 The thickness and length of the fibres are very variable, but all agree with one another 

 as to their tendency to take in foreign bodies. The specimen proved to be overcharged 

 with filaments, one of which is represented on PL VIII. fig. 5. 



Colour. — Outer surface and parenchyma pale dirty yellowish, skeletal fibres pale 

 grey-yellowish. 



Habitat.— Citation 188, September 10, 1874, lat. 9° 59' S., long. 139° 42' E.; 

 depth 28 fathoms, green mud. 



Cacospongia oligoceras, n. sp. (PL VI. fig. 13). 



This species is represented only by a small fragment of massive shape, with the outer 

 surface, where not covered with mussel-shells, stones, &c., provided with low conuli. Its 

 exterior agrees closely with that of Oligoceras collectrix, Schulze, but there is a great 



