466 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



(pi. 43, fig. 4), taken at station D5629, confirms his suspicion that 

 the species may be vasiform as well as plate-like. It is a stony 

 conical cup. 50 mm. high and 70 mm. across the mouth. The Avail 

 is smooth and y 2 to 2y 2 mm. thick. The cup is broken open at the 

 base. The apertures of the (presumably) efferent canals, scattered 

 over the inner face, are about 150 jx in diameter: those of the afferent 

 canals, on the outer surface, of about same size. 



The desmas are firmly united. The rounded fenestrae perforating 

 the skeleton are smaller, and the skeleton is denser, in the super- 

 ficial region than in the interior, where the fenestrae measure 70-175 

 \), in diameter. What may be called a typical desma has a total 

 length of about 340 p.; thickness of epirhabd 35 pi. But the desma 

 varies a good deal both in size and shape. (See Sollas. 1888, p. 

 323.) The epirhabd may be nearly straight or very curved. The 

 clads, few in number, project at about right angles to the adjoining 

 part of the epirhabd, and may be short or comparatively long. The 

 articular surfaces are at the ends of the clads and epirhabd. They 

 are concave and frequently much expanded (pi. 51, fig. 7, where the 

 concave face of the articular process (a. p.) is applied to the other 

 desma) but the articulation is sometimes only one of apposition 

 (pi. 51, fig. 5.) Perhaps the latter condition indicates an earlier 

 stage of zygosis. 



The spinose tubercles on the desma vary in shape and frequency. 

 They may be simple spines, or bifurcated and thus bidentate (pi. 51, 

 figs. 4, 7). Very frequently the bifurcation, more strictly speaking 

 the formation of new outgrowths simulating division, is continued 

 (pi. 51, fig. 7), and we eventually get the characteristic tubercles of 

 the species, which consist of an irregular rosette of 3 to 6 or 7 spines 

 surrounding a convex area (pi. 51, figs. 4, C). The spinose tubercles 

 occur on epirhabd and clads, often abundantly, yet many desmas are 

 comparatively smooth. At the surface of the sponge, the tubercles 

 are small and simple, thickly crowded, often blunt, terminating as 

 described by Sollas (1888, p. 320) at about the same level and thus 

 giving support to the dermal membrane. The rosette-like tubercles 

 described above are identical with those figured by Topsent (1904, 

 pi. 8, fig. 7). 



The oxeas which project in small bundles over both surfaces are 

 350-420 \>. long and about 6 \i thick. They are thus smaller than in 

 the Amboina specimen described by Sollas, in which they measured 

 750 by 8 \l. The oxeas measured by Topsent (1904, p. 64) in a 

 specimen from the Azores reached a length of 700 \i with a thickness 

 of only 1.5 to 3 jx. 



The species has been recorded for widely separated parts of the 

 Atlantic, and for the Band* Sea. (See Lendenfeld, 1903.) 



