234 
HYALONEMA (HYALONEMA) TYLOSTYLUM. 
The terminal anchors are 34-85 n long, from less than a third to more than 
two fifths of the whole spicule, and 19-53 m broad. The proportion of their 
length to their breadth is 100 to 46-88, on an average 100 : 58.3. As in the 
large macramphidiscs, the relative breadth of the anchors is, roughly speaking, 
in proportion to the size of the spicule. In the smaller small macramphidiscs, 
under 170 n in length, the proportion of anchor-length to anchor-breadth is 
100 to 46-62, on an average 100 : 55.8; in the larger, over 170 m in length, 
this proportion is 100 to 48-88, on an average 100 : 60.8. 
The individual teeth are curved strongly in their basal part. Distally the 
curvature decreases, and it is on the whole such that the end-parts of the teeth 
are usually slightly convergent. 
In one of the spicule-preparations I found an amphidisc with a supernu- 
merary anchor-crowned ray arising from the central tyle. The main shaft is 
110 m long and 2 n thick. The central tyle is 4 fx in diameter. The main ter- 
minal anchors are 32 n long and 31 m broad. The supernumerary ray is 27 m 
long. Its terminal anchor is 18 m long and 28 n broad. The ends of adjacent 
teeth of different anchors lie in a straight line. The main shaft and the super- 
numerary ray are densely spined throughout. This spicule might be termed a 
triadisc. 
The ynicramphidiscs (Plate 69, figs. 15-18) are 29-49 m long, most fre- 
quently about 35 n long. The shaft is straight, 0. 7-1.1 n thick, and either uni- 
form in thickness, cylindrical throughout, or slightly and gradually thickened at 
or near the middle to a central tyle which is sometimes 1.3 m in diameter. The 
shaft is either quite smooth or it bears a larger or smaller number of minute 
spines. The anchors are 5-11 n long, a quarter to a fifth of the whole spicule, 
and 5-9 m broad. The proportion of their length to their breadth is 100 to 65- 
150, on an average 100 : 88.9. The anchors of the largest micramphidiscs, that is 
those over 40 n in length, are, on the whole, more slender than those of the 
others. The proportion of anchor-length to anchor-breadth is in these large 
micramphidiscs 100 to 75-87, on an average 100 : 80.8. The individual anchor- 
teeth are curved so that their end-parts are either parallel or convergent. 
The nearest allies of the sponges above described are the species Hyalonema 
( Hyalonema ) placuna and H. (II.) tenuifusum described in this Report. From 
these they differ by possessing tylostyle megascleres ; by being destitute of 
microhexactines with two longer opposite (apical) and four more or less reduced 
(lateral) rays; by the smaller size of the distal rays of their dermal pinules, and. 
by other characters. 
