REPORT ON THE DEEP-SEA KERATOSA. 



39 



Holopsamma cretaceum, n. sp. (PL VII. figs. 7A-7C). 



Habitat.-— North Atlantic, Station 70; June 26, 1873; lat. 38° 25' N., long. 

 35° 50' W.; depth, 1675 fathoms; bottom, Globigerina ooze. 



Sponge massive, lumpy, forming irregular roundish or bulbous chalk-like masses, 

 composed almost entirely of Globigerina shells, cemented together by a scarce maltha. 

 The porous surface exhibits conical depressions ; the prominent ridges between them 

 bear series of oscula. 



Holopsamma cretaceum is represented in the Challenger collection by a single dry 

 specimen, an irregular tuberose white lump, the diameter of which varies between 20 

 and 50 mm. The dry sponge is like a piece of common rough chalk, white and very 

 friable. Nearly the whole body is composed of Globigerina ooze, the shells of which 

 are cemented together by a small quantity of maltha. No symbiotic Spongoxenia 

 inhabits this species. 



The single specimen of the Challenger collection is figured by Miss Traill from two 

 sides on PI. VII. figs. 7A, 7B. It is very friable, like chalk, represents an irregular, 

 tuberose, roundish lump, compressed from two sides, and exhibits about a dozen 

 unequal funnel-shaped depressions of the surface. These funnels are 8 to 12 mm. in 

 diameter and are twice as broad as the prominent ridges between them (4 to 6 mm. in 

 diameter). The ridges bear series of black points, which seem to be the oscula of the 

 exhalent canals ; they are absent in the white surface of the funnels, in which only the 

 smaller pores of the inhalent canals are to be seen. 



After having dissolved the calcareous matter of the skeleton by hydrochloric acid, 

 there remains a very small residuum, composed of the scarce maltha connecting the 

 shells of the Globigerina ooze and groups of branched canals (fig. 7C). These canals 

 have thin structureless walls, and their diameter varies greatly ; the smallest branches 

 seem to proceed from the porous thin dermal membrane and are colourless ; the canals 

 of medium size bear sand in their walls and exhibit roundish dilatations, which seem to 

 be the remnants of the flagellated chambers. The large canals, which open on the surface 

 by the oscula above mentioned, are easily visible, since their thin wall is impregnated 

 with black pigment-spots ; the black oscula have a diameter of 0*4 to 0*6 mm. 



Holopsamma argillaceum, n. sp. (PI. VII. figs. 6A, 6B). 



Habitat— South Pacific, Station 294 ; November 3, 1875 ; lat. 39° 22' S., long. 

 98° 46' W.; depth, 2270 fathoms; bottom, red clay. 



Sponge massive, lumpy, forming irregular roundish or bulbous masses, composed 

 almost entirely of mineral particles characteristic of the red clay, and cemented 



