474 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Avhere they end in the conuli; these fibers sometimes branching in 

 dendritic fashion. All (primary) skeletal fibers alike; hollow, the 

 axial cavity surrounded by a noncellular pith, which in turn is sur- 

 rounded by the spongin of the fiber; the latter containing abundant, 

 regularly disposed cells or cavities in which cells once were, such 

 cells presumably spongoblasts, once superficial but becoming engulfed 

 during the growth in thickness of the fiber. 



IANTHELLA FLABELLIFORMIS (PaUas). 



Spongin. ftabellifonnis Pallas, 1766, p. 380. 



Ianthella flabelliformis Polejaeff, 1884, p. 37.— Ridley, 1884, pp. 392, 



601. — Lendenfeld, 1888, p. 23 (older synonymy given in detail) ; 1S89, p. 



696.— Hentschel, 1912, p. 434. 



Station 5145, one large dried specimen. Sponge a lamella 600 mm. 

 high and about as wide, narrowing to a thick, short, stalk-like base; 

 lamella in general about 4 mm. thick, at the very base fully 20 mm. 

 thick. In the region of the stalk one surface is somewhat convex 

 and one somewhat concave, this difference disappearing a short 

 distance above the stalk. A difference between the two surfaces 

 with respect to oscula, pores, and perhaps conuli, has been recorded 

 for this species (Lendenfeld, 1889, p. 696; Hentschel, 1912, p. 434). 

 But in the Albatross specimen oscula 2 mm. and less in diameter 

 are, at any rate, abundant on both surfaces, and the conuli of the 

 two surfaces are alike; pores indistinguishable. Color of specimen, 

 black, but the natural color is known to be a bright yellow, which 

 quickly changes on exposure to the air to a dark violet blue. The 

 species may reach a height of 1,000 mm. (Lendenfeld, 1888, p. 23). 



The radial fascicular fibers in the lower part of the sponge have 

 the character of more or less cylindrical bundles, but throughout the 

 body in general they form thin reticular lamellae, placed edgewise 

 to the sponge surfaces and about 3 mm. apart ; these are the bands 

 mentioned by Lendenfeld. The connectives have the character of 

 simple or slightly fascicular fibers, and the system of square or 

 rectangular meshes formed by them with the radial bands is quite 

 regular, closely resembling the photograph of /. basta given by 

 Lendenfeld (1889, pi. 47). But, as recorded by Lendenfeld (1888, 

 p. 24), the connectives in /. fLctbelMformis may form bands like those 

 formed, doubtless through continual branching and anastomosis, by 

 the radial fibers. 



The specimen considering its area is thin for the species, and the 

 conuli, distributed at intervals of about 3 nun. along the edges of 

 the radial bands, are very low. They are not over 1 nun. high, and 

 for the most part simple, occasionally divided close to the apex 

 into two or three points. Correspondingly the supporting fibers of 



