REPORT ON THE DEEP-SEA KERATOSA. 



31 



Ammoconia auloplegma, n. sp. (PI. VIII. fig. 4). 



Habitat. — Tropical Atlantic (between the Canary and Cape Verde Islands), Station 

 89; July 23, 1873; lat. 22° 18' N., long. 22° 2' W.; depth, 2400 fathoms; bottom, 

 Globigerina ooze. 



Sponge reticular, composed of anastomosing cylindrical branches, the porous wall of 

 which is calcareous, composed of agglutinated Globigerina shells. 



Ammoconia auloplegma forms a loose roundish network, 12 to 16 mm. in diameter, 

 of the same form as that of the following species, figured in PI. VIII. fig. 5. The 

 cylindrical branches composing it are, however, only half the size of those of the latter, 

 viz., 0'5 mm. in diameter. They j>resent the same aspect as the free cylindrical tubes 

 of Ammosolenia rhizammina, so that the former sponge may be derived from the latter 

 simply by the anastomosing of the branches. The structure of the canal- walls, too, is 

 the same in both. After the removal of the opaque calcareous matter by hydrochloric 

 acid, there remains a delicate membrane, pierced by numerous circular pores (p). The 

 membrane contains small stellate cells scattered in a granular maltha (m), and a few 

 larger dark granular cells, which may be amoeboid wandering cells. Seen from the 

 inside, the porous wall is covered here and there by small irregular flakes of epithelium, 

 composed of minute granular cells, probably the remnants of the flagellated entodermal 

 epithelium (n). Fig. 4 on PI. VIII. is semi-diagrammatic, exhibiting these different 

 elements united as they would appear in a transverse section of the living sponge. 



Ammoconia sagenella, n. sp. (PI. VIII. figs. 5A, 5B). 



Habitat.— North Pacific, Station 256; July 21, 1875; lat. 30° 22' N., long. 

 154° 56' W. ; depth, 2950 fathoms ; bottom, red clay. 



Sponge reticular, composed of anastomosing cylindrical branches, the porous wall of 

 which is siliceous, composed of sponge spicules and volcanic debris. 



Ammoconia sagenella (in PI. VIII. fig. 5A magnified four times) forms a loose 

 network, composed of short, cylindrical, anastomosing branches. The diameter of the 

 reticular sponge is 12 to 20 mm., that of the branches 1 to 2 mm., that of the meshes 

 of the network 2 to 4 mm. The thin wall of the tubes is rather hard and firm, pierced 

 by numerous very small circular pores (fig. 5B, p). The xenophya composing the wall 

 are siliceous, partly fragments of various sponge spicules, partly small polyhedral or 

 more rounded sand-grains, the characteristic constituents of the red clay (x). Some 

 fragments of the tubes, treated with carmine, and seen from the inside, exhibited here 

 and there between the pores small epithelial flakes, composed of small granular cells ; 

 they are probably the remnants of the flagellated entodermal epithelium. 



