414 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



the base to the apex, which is free. But some extend from tube to 

 tube, fastening the tubes together; in these the connection with each 

 tube is expanded, the middle part slender. These tendril-like struc- 

 tures, it would seem from the anatomy, provide the sponge tubes 

 with a specialized means of gaining support, in that they can es- 

 tablish connection between tubes which are some distance apart. 



Abundant small canals extend in radially from both inner and 

 outer surfaces of the sponge. The apertures on the inner surface,, 

 oscula, are about 0.5 mm. or less in diameter; not covered in by 

 reticular membranes. On the outer surface, the canals (afferent) 

 are covered in b} 7 the dermal reticulum. 



The slender longitudinal fibers, 20-30 \i thick, are as Hentschel 

 states, typically unispicular, although such fibers occur containing 

 in places two or even three rows of spicules. The slender fibers com- 

 bine to form bundles as in Hentschel's specimens; this feature is- 

 variable and is less marked in the specimens from station D5136 than 

 in the others. The meshes of the unispicular renieroid network 

 extending between the longitudinal fibers are 3, 4, or 5 sided, with 

 spongin showing at the angles. The dermal reticulum is only the 

 most superficial part of the general skeletal network. The oxeas 

 measure commonly 80 by 4 u, reaching 90 by 5 jjl, and are there- 

 fore somewhat larger than in the type specimens. 



Hentschel (1921) has called attention to the unique character of 

 the skeleton in this form, and to the resemblance offered to certain 

 species of Reniera. The long iibers are, however, of a distinctly 

 chalinine type, and the habitus is that of Siphonochalina. 



SIPHONOCHALINA CRASSIFIBRA Dendy. 

 Siphonochalina crassifibra Dendy, 1889, p. 82. 



Several specimens, along shore, Tataan, Tawi-Tawi. 



One specimen is a single tube as if independent, attenuated at 

 extreme base. Four others are bunches of tubes which ascend from 

 a common basal part, side by side; lateral fusions common; from 

 4 to 12 tubes in a bunch. The tubes are cylindrical with some 

 tendency to form enlargements which may be roughly annular, 

 but the surface is fairly even. The cloaca extends throughout the 

 tube; generally with only one (apical and large) cloacal aperture, 

 but in some tubes there are also smaller lateral apertures. Wall of 

 tube relatively thick, one-third to one-quarter total diameter of 

 tube. The tubes range in height from 30 to 120 mm., in diameter 

 from 10 to 23 mm. Color in life, lilac. Sponge firm but some- 

 what compressible and elastic; tough. 



Dermal membrane, where uninjured, is finely and uniformly 

 porous; pores in the meshes of the dermal reticulum. The usual 



