HEXACTINELLIDA. 19 



The monoxyhexasters (VI. 3e^) are fairly common; they are about 100/a in diameter. 

 The calycocomes (VI. 3f, f^) are 220jli in diameter, the primary rays being 14/x, in 

 length; the solid hemispherical cup-shaped capitulum is 9/x in length and breadth; 

 the secondary rays form a plume-like circle of six to eight slender, slightly divergent 

 rays, tipped with very small disks. 



Holodiscohexasters (VI. 3g), 96^ in diameter, are very rare; the short primary 

 rays, 9/a in length, divide into two to four secondary rays ending in disks with four 

 to five sharp recurved teeth. The microdiscohexasters (VI. 3h) are 40/li in diameter. 



This new species closely resembles A. pilosa in its outward appearance, but differs 

 from that species chiefly in the structure of the gastral membrane (VI. 3), and in the 

 absence of the holoxyhexasters, so abundant in A. pilosa. 



Numerous macerated fragments, consisting' solely of a skeletal framework of 

 bundles of diactins with large hexactins, and occasionally autodermal pentactins, were 

 obtained from 10-20 fathoms in McMurdo Bay. These, together with a sack-shaped 

 skeleton and a tuft, 20 cm. in length, of diactin and anchor-like pentactin basalia, found 

 by a sledge party on the ice, all belong to Aulorossella levis. 



Winter Quarters : (1) two large specimens taken in the trawl 150 yards south of 

 the ship, in 18-36 m. (10-20 fms.) ; (2) two small young specimens from No. 5 hole 

 (Seal Hole), August 7, 1902, 325 m. (178 fms.); (3) Macerated fragments from 

 McMurdo Bay, 18-36 m. (10-20 fms.). 



AULOBOSSELLA LONGSTAFFI.* 



(Plate II., fig. 4, and Plate VII., figs, la-k.) 



Sponge* barrel-shaped, almost solid, with only a very shallow gastral cavity with 

 wide circular orifice having a thin unarmed edge. Surface irregularly tuberculated and 

 ridged, pleuralia almost entirely absent (there being only two or three scattered about). 

 Inferior end without a definite root-tuft, but with a few large conules with a few 

 basalia. Autodermalia thick pentactins, autogastralia thick hexactins. Amongst the 

 parenchymalia curious tetractins. 



The sole specimen of this interesting species is 6 " 8 cm. in height, 3 • 9 cm. in 

 breadth about the middle ; the orifice is nearly 2 cm. in diameter, and the gastral 

 cavity only 1 ' 4 cm. in depth. In its stumpy fleshy appearance, the specimen some- 

 what resembles a kind of cactus plant. Both the dermal and gastral surfaces are 

 smooth and glistening, and almost opaque, scarcely showing any trace of a hypogastral 

 network. The shallow gastral cavity has in its floor two depressions separated by a 

 ridge. 



The skeleton is mainly constructed of bundles of diactins ; and in addition to 

 these, large regular hexactins are distributed in the sponge body. 



* The species name is given in honour of Mr. Longstaff, whose munificent donation of £25,000 made 

 possible the fitting-out of the expedition. 



voi,. III. 2 K 



