6 R. KIRKPATRICK. 
considerable amount of variation, and will be described separately as A, B, and C. 
Had they not come from the same spot, I would probably have regarded B and C as 
representing a variety of the typical form. All the specimens possess a well-developed 
root-tuft, therein differing from those obtained from Kerguelen and other localities in 
the Southern Indian Ocean, and from near the mouth of the Rio de la Plata in the 
South Atlantic. Prof. Schulze mentions in the ‘ Challenger’ Report (p. 139) that he 
had never found the loose root-tuft, which Carter represents in his diagrammatic figure 
(2, pl. x., fig. 4), and he considers this modification in the original specimen to 
be conditioned by the looser nature of the substratum. 
Prof. Ijima observes (5, p. 5) that “a case of one and the same Hexactinellid 
species being firmly fixed when growing on a hard substratum, but producing a root-tuft 
when living on a soft bottom, has never as yet been shown to exist.” The ‘ Discovery ’ 
and ‘Challenger’ specimens of /ossella antarctica seem to me to furnish instances of 
specimens of the same species being fixed solidly or by a root-tuft in accordance with 
the nature of the bottom. In spite of the considerable range of variation in bodily 
form, mode of fixation and spiculation, the Antarctic and the more northerly forms 
appear to me to come within the limits of one and the same species, but I regard the 
latter as belonging to a variety—var. solida. The microdiscohexasters, too, are 
considerably larger in the typical Antarctic specimens than in the northern variety. 
If the anchor spicule figured by Schulze (6, pl. lv., fig. 12) really belongs to the 
specimen from which it was obtained, its presence suggests that the sponge, now solidly 
fixed without a root-tuft, was derived from a form with such an appendage. 
Specimen A.—(Plate I, fig. 1, and Plate IV., fig. 2 a—g.) 
This, which is the smallest of the three specimens, closely resembles the original 
one obtained by Sir James Ross and diagrammatically figured by Carter (2, pl. x., 
fic. 4). The tatal length is 7 em., the body being 4 em., the root-tuft 2 cm., and 
the oral fringe nearly 1 cm. in length. The greatest breadth is 3em. The velum 
is about 7 mm. from the surface of the body. Numerous oval or pyriform buds, each 
about 2 mm. in length, are present amidst the dense tangle of the velum. The orifice 
is narrow, oval, about 1 em. in length, and acute-angled at each end. ‘The diactin 
marginalia surrounding it form a sloping palisade which meets in the middle line 
above, the inclination increasing from without inwards. The root-tuft, which encloses 
débris of worm-tubes, fragments of Polyzoa, etc., is formed of pentactins in the shape 
of four-pronged anchors with thick curved prongs. The surface of the body is level, 
though here and there small, barely perceptible conuli occur. The skeleton is mainly 
formed of long wavy bundles of slender diactins. 
Spicules.—The principalia are long slender diactins, often with roughened, 
rounded or bulbous ends. There are also parenchymal regular hexactins (IV., 2a) 
scattered about. The marginalia are sharp-pointed oxydiactins 1°5 em. long and 
160» thick. The basalia are long, slender, four-pronged anchors 4 em. in length, with 
