HYALONEMA (HYALONEMA) SP. 243 
Hyalonema (Hyalonema) sp. from Station 3684 (A. A. 17). 
Plate 80, figs. 1-16. 
A small fragment about 10 mm. long with several stalk-spicules was col- 
lected in the Central Pacific, Station 3684 (A.A. 17) on 10 September, 1899; 0° 50’ 
N., 137° 54’ W.; depth 4504 m. (2463 f.); it grew on light yellow-gray Globigerina 
ooze. This fragment appears to have formed part of a species of Hyalonema 
_not sufficiently well-preserved for specific determination. 
The spicules of this fragment are pentactine pinules with long distal ray, 
pentactine pinules with short distal ray, diactine pinules; hexactine, pentactine, 
and diactine megascleres; acanthophores; stalk-spicules; microhexactines; 
macramphidises; and micramphidiscs. 
The pentactine pinules with long distal ray (Plate 80, fig. 16). The distal 
ray in these spicules is 375-670 » long, and 5-8 u» thick at the base. It tapers 
gradually towards the fine-pointed end, and bears very small and rather sparse 
strongly inclined spines. These decrease in size distally. The lateral rays are 
spiny and 60-80 u long. 
The pentactine pinules with short distal ray (Plate 80, fig. 14). In these 
spicules the distal ray is 170-260 u long, and 4-8 u thick at the base. It bears 
rather strongly inclined spines, which are larger than in the pentactine pinules 
with long distal ray. The maximum thickness of the distal ray, together with 
the spines, is usually 11-16 u. The lateral rays are spiny and 60-70 u long. 
The diactine pinules (Plate 80, fig. 15). The total length of these spicules 
is usually 0.7-0.8 mm. The distal ray is 390-480 u» long, 5-8 uw thick at the base, 
and covered with small, strongly inclined spines. The lateral rays are reduced 
to smooth, cylindrical, terminally rounded protuberances, (measured from the 
axis of the spicule) 6-17 » long. The proximal ray is 305-330 u long. 
The pentactine megascleres have a proximal ray 450-600 uw long, and 10-35 u 
thick at the base. The lateral rays of the same spicule are more or less unequal. 
The length of the smallest is not infrequently only two thirds of that of the long- 
est, sometimes even less. The lateral rays are straight, conical, blunt, and 170— 
560 » long. 
The hexactine megascleres are 0.7—-1.8 mm. in diameter, and have rays 20-— 
40 uw thick at the base. 
The diactine megascleres are centrotyle. The diameter of the central tyle 
is sometimes as much as twice as great as the thickness of the adjacent parts of 
the spicule. 
