324 
HYALONEMA (OONEMA) BIANCHORATUM PINULINA. 
of specimen 
a 
of specimen 
b 
of both speci- 
mens together 
Length n 
limits 
110-200 
118-187 
110-200 
most frequently about 
164 
164 
164 
Shaft, thickness, limits n 
13-20 
14-20 
' 13-20 
length, limits n 
0 
46-87 
50-81 
46-87 
breadth, limits tx 
. 
74-135 
85-126 
74-135 
Terminal 
anchors 
proportion of anchor- 
length to anchor- 
breadth 
limits 100 to 
153-185 
130-172 
130-185 
average 100 to 
167.5 
153 6 
161.1 
proportion of anchor- 
length to total length 
of the whole spicule 
limits 1 : 
2-2.5 
average 1 : 
2.3 
In these amphidiscs the shaft is straight, regularly cylindrical, destitute of 
a central tyle, and perfectly smooth. 
The proportion of the length of the anchors to the total length of the whole 
spicule is in both specimens together, as stated above, 1 to 2-2.5, on an average 
1 : 2.3. The difference between total length and anchor-length is in the small 
macramphidiscs, in contradistinction to that of the large, on the whole the 
greater the shorter the spicule. In the longer small macramphidiscs, over 
180 n in length, the above proportion is 1 to 2. 2-2. 3, in the shorter, under 130 n 
in length, 1 to 2. 4-2. 5. 
The terminal anchors are composed of from eight to twelve teeth. Eight 
is the most frequent number, but small macramphidiscs with from nine to 
twelve are by no means rare and in no way abnormal. The position of the teeth 
of the two terminal anchors of the same spicule is alternate. The individual 
teeth have a T-shaped transverse section. The upper band-shaped part is, 
in its middle-part, 22-30 n broad and attenuated both distally and proximally 
(Plate 82, fig. 26). It is not only longitudinally, but also transversely curved, 
concave to the shaft (Plate 84, fig. 27), and usually rounded, very rarely pointed, 
at the end. The keel, that is the part corresponding to the lower stroke of the 
T, is low distally but attains a great height and thickness proximally (Plate 84, 
figs. 26, 28, 32). The outer contour of the tooth, when seen in profile, appears 
as a line strongly curved near the base and at the tip, but only slightly curved 
in its middle-part. The middle-part of this line diverges at an angle of 20-30° 
from the shaft; its end-part is convergent to the shaft. The end-parts of the 
