HYALONEMA (HYALONEMA) OBTUSUM. 
153 
Hyalonema (Hyalonema) obtusum, sp. nov. 
gracilis, var. nov. 
Plate 33, figs. 1-24; Plate 34, figs. 1-19; Plate 35, figs. 1-37; Plate 36, figs. 1-45; Plate 37, figs. 1-22; 
Plate 38, figs. 1-8; Plate 39, figs. 1-10. 
robusta, var. nov. 
Plate 39, figs. 11-41; Plate 40, figs. 1-22. 
Two specimens were trawled at two stations in the Tropical Pacific; - 
Hyalonema (H.) obtusum var. robusta at Station 3681 (A. A. 2) on 27 August, 1899; 
28° 23' N., 126° 57' W. ; depth 4330 m. (2368 f.) ; it grew on light brown volcanic 
ooze; the bottom-temperature was 34.6°. H. (H.) o. var. gracilis at 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. These sponges are distinguished 
from their nearest allies by the stout truncate or terminally rounded spines on 
their macramphidisc-shafts. To these the name refers. 
Although on the whole very similar in their spiculation, these two sponges 
differ in respect to their external appearance and certain characters of their 
skeletal element so that I consider them distinct varieties. The spicules of the 
specimen from Station 3681 (A. A. 2) are generally speaking stouter, those from 
Station 3684 more slender. 1 therefore name the former H. (II.) o. var. robusta, 
and the latter H. (II.) o. var. gracilis. 
Shape and size. The specimen of var. robusta is rather fragmentary, its super- 
ficial parts having to a great extent been lost. It consists (Plate 39 , fig. 33) of a 
flattened body, 65 mm. long, 12 mm. thick, and 42 nun. broad above. Below 
it becomes narrower, and there protrudes from its rounded lower end a bundle 
of stalk-spicules. This bundle, where it arises from the sponge-body, is about 
2.6 mm. thick. The stalk-spicules forming it are broken off at a distance of 
35 mm. from the lower end of the sponge. 
The specimen of var. gracilis is well-preserved, but destitute of the stalk; the 
sponge-body having apparently been pulled off the stalk-spicules by the trawl. 
It has the shape of a short and broad spindle or top (Plate 33 , fig. 15), is 47 mm. 
long (high), and has a maximum transverse diameter of 30 mm. The lower end, 
from which in life the large stalk-spicules arose, is now simply rounded off. 
The upper end consists of a gastral cone closely enveloped by the thin, frill-like 
margin of the wall surrounding the gastral cavity. The cone (Plate 33 , fig. 16a) 
is 9 mm. high, nearly cylindrical, circular in transverse section, terminally 
rounded, 6 mm. thick at the base, and 4 mm. at the end. Its end is slightly 
