36 THE SPONGES. 



transverse diameter, tapering gradually toward the ends, which are apt 

 to break off or remain concealed in the cement. The comitalia are verj'^ 

 slender, often only 6 or 8 /a thick. The length of the principalia may 

 exceed 20 mm., and they are frequently though not always bent at the 

 middle, as in the similar spicules o( B. jjhocnix (Schulze, 1899, p. 21). 



The reticulum of silicious beams constituting the basal plate presents no 

 peculiarly characteristic features, agreeing in general with the description 

 given by Ijima (1901) for M. okinoseaiia and H. kamei/amau 



Regadrella delicata, sp. nov. 



Plate 3, Figs. 7, 8. Plato 4, Figs. 3, 11. 



Diagnosis. The marginal spicules round the sieve-plate are stauracts, the longitudinal 

 axes of which are not included in the skeletal bundles of the body wall. The superior 

 rays of the stauracts are accompanied by slender parenchymalia, not by the parenchy- 

 raalia principalia. Species close to Regadrella phoenix 0. Schm., agreeing with it in 

 general spiculation. 



Station SJfiJf, one specimen. 



The specimen is fragmentary, including a part of the lateral wall of the 

 sponge, which had been ripped open longitudinally. In packing, the piece 

 was compressed so that it reached me in the shape of a folded plate, the line 

 along which the folding had taken place corresponding with the long axis 

 of the sponge. This plate-like fragment had a length of 150 mm. and a 

 greatest width of 50 mm. Its upper edge is formed by the margin of the 

 sieve-plate area, and seems to be vminjured. The dermal and gastral sur- 

 faces of the lower part of the piece are shown in Fig. 11, Plate 4. 



When the two halves of the specimen, which had been folded together, 

 were separated, some idea of the natural shape of the sponge was obtain- 

 able, and it could be seen that the sac tapered markedly toward its upper 

 end. The upper edge is 25 mm. long. How much of the natural periphery 

 of the sieve-plate area this represents could not be ascertained, although the 

 curvature of the wall indicates that it represents a very large part. 



The wall of the sac is thin, about 1.5 mm. thick. The rounded parietal 

 apertures are mostly 2 to 1.5 mm. in diameter, except in the extreme upper 

 part of the sponge, where the diameter is very commonly about 1 mm., 

 although much smaller apertures are here present. The apertures exhibit 

 an imperfect arrangement in oblique or nearly transverse rows, and are 



