HYALONEMA (PHIALONEMA) PATERIFERUM. 
371 
The small macramphidiscs are in the forms A and B, according to Wilson 
( loc . cit.), 60-100 m long; in form C 68-100 n, most frequently about 76 m; in 
form D 63-96 m long, most frequently about 80 /j.; in form E 87-100 n long, 
most frequently about 95 m; and in form F 75-100 n long, most frequently 
about 93 fj . The thickness of their shafts are in form C 9-13 n, in form D 5-9 //, 
in form E 11-17 m, and in form F 9-13 n- The anchors of these spicules are: — 
in form C 18-28 n long and 40-65 n broad, the proportion of anchor-length to 
anchor-breadth being 100 to 143-333, on an average 100 : 258 ; in form D 
(Plate 52, figs. 5-8) 25-31 n long and 35-60 n broad, the proportion of anchor- 
length to anchor-breadth being 100 to 120-200, on an average 100 : 162; in 
form E (Plate 51, fig. 15) 18-25 long and 52-70 ju broad, the proportion of 
anchor-length to anchor-breadth being 100 to 256-340, on an average 100 : 306; 
and in form F 14-20 m long and 30-58 m broad, the proportion of anchor-length 
to anchor-breadth being 100 to 210-330, on an average 100 : 286. 
The large micramphidiscs (Plate 50, fig. 14; Plate 51, figs. 9-14; Plate 52, 
figs. 27-29) have a shaft 1-3 n thick and cylindrical throughout or slightly 
and gradually thickened in or near the middle. The shaft is beset with irregular 
obtuse spines 0.5-2 /j. long. These are generally very numerous, and usually 
occupy all parts of the shaft with the exception of its ends. The terminal 
anchors are long, rather narrow, and very obtuse. Sometimes their length 
is sufficient to bring the teeth of the two opposite anchors of the same spicule 
nearly into contact with each other (Plate 50, fig. 14; Plate 51, fig. 9). The 
individual teeth arise steeply from the shaft. They are curved only slightly 
in their basal part, but strongly and more or less abruptly bent down a short 
distance from their origin. Their distal and middle-parts, beyond this bend, 
are only slightly curved or straight and enclose a small angle, 20° or less, with 
the shaft-axis. Sometimes this angle is 0 (Plate 52, fig. 8); then they are 
parallel to the shaft. 
The large micramphidiscs of forms A and B are generally simple. Excep- 
tionally, however, they have more than two anchor-crowned rays. The ordinary 
simple ones are, according to Wilson (loc. cit.), 50-80 /x long, and have anchors 
which are slightly more than a third of the whole spicule in length and com- 
posed of eight teeth. One of the large micramphidiscs with more than two 
anchor-crowned rays, measured by Wilson (loc. cit.), was 72 /x in maximum diam- 
eter, and had five rays, three of which bore terminal anchors. The large 
micramphidiscs of form C are 49-66 m long, most frequently about 57 n, and 
have anchors 15-28 ^ long, less than a third to nearly half of the whole spicule, 
