SILICIOUS AND HORNY SPONGES WILSON. 341 



TUBERELLA CILIATA, new species. 



Plate 39, fig. 1. 



A specimen from station D5641. 



Sponge massive, amorphous, partially breaking up into rounded 

 lobes. Surface very minutely and thickly conulose, and finely hir- 

 sute with spicules that project in general about 1 mm. There is 

 some indication that small oseula, now closed, are scattered sparsely 

 over the surface. Pores closed, but arrangement of subdermal cav- 

 ities indicates that they are scattered. Color whitish brown. 



There is a translucent, gelatinous-looking ectosome about one-half 

 millimeter thick, not fibrous but collenchymatous. The collenchym'a 

 extends down into the choanosome, accompanying the larger canals 

 which connect the interior with the ectosomal spaces. 



The ectosomal cavities include (1) shallow, interconnecting sub- 

 dermal spaces about 50 y. deep, immediately below the thin surface 

 membrane, which is only about 4 y. thick; and (2) 'a system of inner 

 spaces lying close to the choanosome, and from which relatively 

 large canals pass into the interior. The inner ectosomal spaces are 

 commonly about 175 \t. deep; they interconnect and are much more 

 conspicuous than the true subdermal spaces. Just bene'ath the latter 

 the ectosomal cells are elongated parallel to the floor of the space, 

 but there is no distinctly differentiated fibrous stratum. 



The body is well filled with very numerous styles, 1,400-2,000 by 

 20-36 y.; straight, or slightly curved or bent; tapering toward the 

 small, rounded, basal end as well as toward the pointed apex ; in the 

 peripheral region curving radially to the surface, the superficial ones 

 projecting in the conuli, a few in each conulus. The spicules are so 

 abundant that there seems at first sight to be no arrangement into 

 fibers, but in 'a carefully macerated slice in which the spicules remain 

 in position, a very imperfect arrangement into spiculo-fibers can be 

 made out. The fibers, or tracts, are dense, without spongin, close 

 together, and imperfectly separated. They all trend toward the 

 surface. 



Very slender ectosomal styles, 1,100-1,300 by 4 pi, about cylindrical 

 in shape, sometimes slightly curved, are abundant. In the ectosome 

 they are radially arranged and grouped indistinctly in bundles, the 

 outer spicules of a bundle projecting from one of the minute conuli. 

 But these tufts of projecting spicules are not far from being con- 

 tinuous with one another. 



Holotype.—C&t. No. 21319, U.S.N.M. 



This is evidently a quite different form from T. aaptos (O. 

 Schmidt) , hitherto the only generally recognized species of the genus. 

 In T. aaptos (Topsent, 1900, p. 285) the larger megascleres form dis- 

 tinct, well-separated spiculo-fibers which radiate from centers, and 



