360 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



wardly projecting bundles of the parenchyma, the cladomes situated 

 at or near the surface. 



4. Sigmas, fairly stout, 8-10 \i long. Abundant at the surface, 

 present also in the interior. In Dendy's specimens the microscleres 

 were found to be not very abundant. 



TETILLA CILIATA, new species. 



Plate 39, fig. 2 



Station D5431, two specimens. The measurements given below 

 refer to the larger one. 



Sponge ovoidal, 35 mm. high, 25 mm. thick. A terminal osculum 

 4 mm. in diameter leads into a cloaca about 5 mm. deep, into which 

 open a number of efferent canals about 1 mm. wide. There is an 

 oscular fringe 3 mm. high. Sponge is hispid with delicate spicules, 

 projecting about 1 mm. beyond the surface. Over the lower end 

 numerous bundles of spicules protrude which unite to form a root- 

 tuft. This holds together a ball-like mass of debris 12 mm. in diam- 

 eter. 



Color light gray to whitish. Sponge moderately compact and firm. 

 If sponge is expanded (pores and canals wide open), as in one 

 specimen, this surface appears coarsely porous, owing to the sub- 

 dermal spaces and peripheral canals being seen through the dermal 

 membrane. 



Ectosome thin, not fibrous nor distinctly marked off from the 

 choanosome: with small subdermal cavities between the radiating 

 skeletal bundles. Dermal membrane, the usual very thin sheet rid- 

 dled everywhere with pores. 



/Skeleton. — Strong radial bundles run from the interior toward 

 the surface, passing in the ectosomal region into divergent brushes. 

 The radial bundles are made up of large oxeas and the rhabdomes 

 of protriaenes. The ectosomal brushes include small oxeas which 

 just reach the dermal membrane, and numerous protriaenes most of 

 which protrude. Oxeas of all sizes are scattered irregularly and 

 thickly throughout the sponge. The oscular fringe includes large 

 oxeas, with smaller sizes, and many protriaenes. The root bundles, 

 in the neighborhood of the sponge body, include large oxeas and 

 small protriaenes, the bulk of the root tuft being made up of very 

 long anatriaenes. 



Spicules. — 1. Oxea. (a) The common type is smooth, equiended. 

 tapering gradually toward each end, 4 mm. — 0.5 mm. by 40-7 pi. 

 The largest oxeas occur in the root bundles. In the oscular fringe 

 they reach a length of 3.5 mm. In the body the common large size 

 is about 3 mm. by 30-35 [jl Very many small oxeas occur, ranging 

 from TOO by 12 y. to 450 by 7 \l. (b) The oxeas of the ectosomal 



