HYALONEMA. 151 
propose a new arrangement, based on the results of my examination of the 
twenty-four Pacific species. 
These results have led me to think that certain characters of the amphi- 
dises could be utilised for this purpose. It is true that the numerous very differ- 
ent forms of these spicules are to a great extent connected by transitions; there 
are, however, in spite of this, some amphidisc-forms not so connected. 
The anchor-teeth of the amphidiscs of most of the Pacific Hexactinellida 
have smooth margins. In five of them, however, there occurs a particular kind 
of amphidiscs with serrated anchor-teeth. For these I establish the subgenus 
Prionema. Of the fifty species previously known there are, I believe, only two, 
H. poculum ¥. BK. Schulze! and H. validum F. KE. Schulze,” in which amphidiscs 
with serrated teeth have been noticed and described. I think it highly probable, 
however, that such amphidises occur in others also, as for instance in H. lusita- 
nicum Bocage, and H. cupressiferum F. EK. Schulze, where they have not been 
mentioned either because they were overlooked — they are generally small and 
clearly visible only with high powers — or because the authors who studied these 
sponges did not consider them of importance. 
Most of the species of Hyalonema examined by me in which the anchor- 
teeth of all the amphidisc forms are smooth-margined, generally have hyper- 
bolic, semispherical, or bell-shaped anchors and measure from about a quarter 
to a third of the whole spicule in length. In some of them, however, the amphi- 
dise-anchors are of other relative dimensions and often also of another shape. 
In five of the Pacific species examined, one of which had been previously de- 
seribed, the anchors of a certain kind of amphidiscs are more or less semi- 
spherical and about half as long as the whole spicule, so that the two anchors 
of the same spicule nearly or quite meet in the middle. For these species I 
establish the subgenus Oonema. Of the species previously described there are, 
besides the one in the A. Agassiz Pacific collection above referred to, four (H. 
lenerum F. IX. Schulze, H. robustum F. E. Schulze, H. globiferum F. FE. Schulze, 
and H. pedunculatum Wilson) which can certainly, and one (H. ovuliferum 
F’. E. Schulze) which can perhaps, be assigned to this subgenus. 
In two of the Pacific species examined by me, one of which had been previ- 
ously described, the anchors of the largest amphidises are small and relatively 
very short and broad. For these species I establish the subgenus Phialonema. 
'F. EB. Schulze. Rept. Voy. Challenger, 1887, 21, p. 208. (This serration is not shown in the 
figure of a macramphidisce of this species. Loc. cit., plate 33, fig. 4). 
2 F. BE. Schulze. Hexactinellida. Ergeb. Deutsch. tiefsee-exped., 1904, 4, p. 82, taf. 34, fig. 8. 
