HYALONEMA (OONEMA) SEQUOIA. 349 



Hyalonema (Oonema) sequoia, sp. nov. 



Plate 85, figs. 9-21; Plate 86, fig.s. 1-30; Plate 87, figs. 1-7; Plate 88, figs. 1-13; Plate 89, figs. 1-36; 



Plate 90, figs. 1-10; Plate 91, figs. 1-6. 



One specimen of this species was trawled in the Central Tropical Pacific, 

 at Station 4740 on 11 February, 1905; 9° 2.1' S., 123° 20.1' W.; depth 4429 

 m. (2422 f.); it grew on a bottom of dark gray Globigerina ooze; the bottom- 

 temperature was 34.2°. Most of its superficial pinules attain a very large size, 

 exceeding the ordinary pinules of other hexactinellids in dimension as Sequoia 

 gigantea does the other conifers. To this the name refers. 



Shape and size. The single specimen is much torn (Plate 86, fig. 8). It 

 appears to be part of a wall, 4-6 mm. thick, of a wide tube or funnel. The 

 specimen is without the stalk, and when laid down flat is 105 mm. long (high) 

 and 116 mm. broad. A stalk, 84 mm. long and broken off at the end, arises 

 from one end. The upper part of the specimen, that is the part opposite the 

 stalk, is composed of lamellae, between the free margin of which remnants of 

 reticulate pore-sieves are spread out. 



The colour in spirit is light brownish yellow. 



The skeleton. The pore-sieves (Plate 86, fig. 7) are supported by para- 

 tangential amphioxes, most of which are small, but a few are large. The latter 

 obviously correspond to the tignules of other hexactinellids. The pore-sieves 

 also contain microhexactines and micramphidiscs. Numerous small macram- 

 phidiscs and large pinules rest on the outer side of the amphioxes support- 

 ing the strands of these reticulate sieves. Although now partly irregularly 

 disposed (Plate 86, fig. 7), I do not doubt that, in life, the axes of the shafts of 

 these small macramphidiscs and of the distal rays of the pinules were vertical 

 to the surface. In the few places where the outer surface of the sponge is intact 

 I found the same spicules, with the exception of the large amphioxes (tignules), 

 and in addition hypodermal pentactines. Numerous slender amphioxes, some 

 hexactine megascleres, masses of microhexactines, and a few large macramphi- 

 discs have been observed in the choanosome of the upper and middle-parts of 

 the body. In the spicule-preparations of these parts have been observed also 

 pinule-like microhexactines, with one ray longer than the other five, and large 

 numbers of micramphidiscs. The pinule-like microhexactines doubtlessly line 

 the canal-walls. The position of the micramphidiscs may be the same. Acan- 

 thophores with one to six stout and terminally interiorly spined rays occur in 

 the basal part of the sponge-body, from which the stalk arises. The stalk con- 

 sists of three thick and a number of slender spicules, all broken off distally. 



