HYALONEMA (HYALONEMA) SP. 243 



Hyalonema (Hyalonema) sp. from Station 3084 (A. A. 17). 

 Plate SO, 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 pinnies with long distal ray, 

 pentactine pinnies with short distal ray, diactine pinules; hexactine, pentactine, 

 and diactine megascleres; acanthophores ; stalk-spicules; microhexactines ; 

 macramphidiscs ; and micramphidiscs. 



The pentactine pinules with long distal ray (Plate 80, fig. 16). The distal 

 ray in these spicules is 375-670 ju long, and 5-8 m 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 n long. 



The pentactine pinules ivith short distal ray (Plate 80, fig. 14). In these 

 spicules the distal ray is 170-260 ^ long, and 4-8 m 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 yu. The lateral rays are spiny and 60-70 yu 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 n long, 5-8 ^ 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 /u long. The proximal ray is 305-330 n long. 



The pentactine megascleres have a proximal ray 450-600 ^ long, and 10-35 m 

 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 M long. 



The hexactine megascleres are 0.7-1.8 mm. in diameter, and have rays 20- 

 40 fi 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. 



