HYALONEMA (HYALONEMA) SP. 221 
The basal acanthophores (Plate 68, figs. 27, 28, 31-33) have from two to 
six rays, the tetractine (stauractine) forms greatly predominating. The tri- 
to hexactines are 230-820 uw long and have rays 11-33 u thick at the base. The 
diactines are 0.7-1.15 mm. long and 7-30» thick near the centre. Most of 
them, particularly the shorter ones, are distinctly centrotyle; their central tyle 
is 12-62 u, which is sometimes 40 » more than the adjacent parts of the spicule 
in transverse diameter. The ends of the rays are thickened and densely cov- 
ered with rather large spines. The remaining parts of the spicules are generally 
smooth. In some stout-rayed tetractines a few spines arise also from the basal 
parts of the rays (Plate 68, fig. 31), and some diactines have a very spiny central 
tyle (Plate 68, fig. 27). 
In the lower part of the body fragments of wncinate anchor-spicules have 
been observed. A spicule of this kind measured is 11 » thick just above the 
anchor. The anchor is 25 » long and 18 uw broad. The anchor-teeth are rather 
numerous, irregular, strongly recurved, and very blunt. 
The microhexactines (Plate 68, figs. 29, 30) are mostly rather regular and 
measure 85-150 » in diameter. In some, two opposite rays are longer than the 
other four. Such microhexactines are sometimes 200 » long and 120 uw broad. 
The rays are 1.5-2.5 » thick at the base, and usually slightly curved a little 
beyond the middle of their length. This curvature is often unequal in different 
rays of the same spicule. 
Occasionally monactine microhexactine-derivates have been observed. A 
spicule of this kind measured appears as a tylostyle 120 u in length and 1 u 
in thickness, with a terminal tyle 3.5 » in diameter. 
Those amphidiscs (Plate 69, figs. 3-5) which can, with some degree of 
probability, be assigned to the sponge, fall into five categories:— large and small 
macramphidises, large and small mesamphidises, and micramphidiscs. 
The dimensions of these five kinds of amphidises are tabulated below :— 
Length of Breadth of Thickness of | Diameter of 
Total length anchor anchor shaft central tyle 
m7 a BK “ KB 
Large macramphidises 280-316 76-120 90-104 9-12 13-18 
Small macramphidises 220-225 77-80 60-70 8 10 
Large mesamphidises 136-168 46-66 22-43 2-6 2-8 
Small mesamphidises 45-69 23 15-18 1.5-2 
Micramphidises 20-29 4-7 6-8 0.6-1 
° 
