HEXACTINELLIDA. 7 
curved prongs 459 » in length. The autodermalia (IV., 2 b-b’) are hexactins (2b’), 
pentactins (2b), and rarely stauractins (2b’), each ray being 75 x 11 p, wholly spined, 
nearly cylindrical, and with blunt end. The pentactins have a well-developed distal 
spiny knob. The hypodermalia are slender oxypentactins with paratangential rays 
with roughened surface and with large prickles. These well-known spicules are not 
figured owing to want of space. The autogastralia (IV., 2c) are large slender 
hexactins, each ray being 173 x 6p. Some of the hexactins, a little below the 
surface, are very large, with the radial rays (each 252 x 21 yu) longer than the 
other four. The intermedia.—The holoxyhexasters (IV., 2d, d'), hemioxyhexasters 
(IV., 2d°), and monoxyhexasters (IV., 2d®, 2d‘), about 164 in diameter, have very 
slender roughened rays, the primary rays being very short or almost absent. The 
calycocomes (IV., 2f) are 80 » in diameter, with long tuberculated primary rays, each 
22 mw in length, ending in a solid hemispherical capitulum from which the only slightly 
divergent secondary rays proceed, presenting, as Carter put it, a dinner-fork-like aspect 
in optical section. Another kind of calycocome (IV., 22) has shorter, thicker, and 
smoother primary rays, a knob-like capitulum, and more divergent secondary rays. 
Medium-sized holodiscohexasters, like those figured by Schulze (6, pl. lv., fig. 15) do 
oceur, but rarely. Plate IV., Fig. 2e, shows a modified hemidiscohexaster 45°5 mw in 
diameter, having bulbous primary rays, and terminal discs little more than a circle of 
spines. The microdiscohexasters (IV., 2h), 50 » in diameter, have long primary rays 
10 » in length, ending in a conical point, the secondary rays being given off in two 
circles a little separated from each other. 
Scattered over the outer surface of the upper part of the specimen are numerous 
small flattened pyriform buds about 52 mm. in length, each bud being supported on 
one or two pleuralia which penetrate it. None of the buds are sufficiently developed 
to show oscule or central cavity. The hypodermal oxypentactins have their paratan- 
gential rays much more curved than in the adult state, and the prickles are hardly at 
all developed. The soft tissues appear much contracted by the strong spirit. A 
section shows an outer trabecular layer surrounding a central mass of choanosome, 
there being only a slight development of an inner trabecular layer, and that so 
contracted as to appear solid rather than reticular. 
Specimen B.—(Plate [., fig. 2, and pl. IV., fig. 53h.) 
This is a large spheroidal sponge, 15°5 cm. in height, with a dense velum 
resembling a tangled thicket, extending about 1*1 cm. away from the surface, and 
with a thick root-tuft. The orifice, which is oval and with sharp angles at each end, 
is 3°7 cm. in length by 1°4 em. in its greatest breadth. 
The marginalia, projecting about 2 cm., lean towards each other across the orifice, 
the innermost layer extending almost horizontally across from one side; on a level 
with the oscule is a depression, looking like a second oscule, but the appearance is due 
