HYALONEMA (PRIONEMA) AGUJANUM. 263 
shaft (Plate 74, fig. 3; Plate 77, figs. 2,3). The end-parts of the teeth are often 
bent rather abruptly inward and they generally converge. The teeth have the 
usual T-shaped transverse section. Their outer and upper band-shaped part 
is, in the larger serrated amphidiscs, nearly uniformly (18-22 w) broad throughout, 
attenuated only slightly distally, and rounded at the end. The lateral and termi- 
nal margins of the teeth are bent down shaftwards and serrated. The serration- 
teeth are triangular, sharp-pointed, and usually directed more or less backwards. 
The lateral ones are 1.5—2 » long and 1-2 u broad, the terminal ones smaller. 
In var. tenuis, form A, and in var. lata the serrated amphidises attain a larger 
size than in var. tenwis, form B; and in var. lata the average relative breadth of 
the anchors is considerably greater than in the two forms of var. tenuis. The 
dimensions of the serrated amphidises are: — 
SERRATED AMPHIDISCS. 
var. tenuis. 
var. lata 
form A form B 
limits yu 90-410 100-342 90-415 
Total 
zeneth ose frequently 320 103, 180 149, 198, 264! 
about yu 
Shaft, thickness yu 3-12 5.5-7.5 3.5-8 
diameter 6-17 12-15 6-14 
Central differences between 
tyle diameter of tyle and 2 5-10 6-8 art is 
adjacent parts of 
shaft be 
, 5-15 8-12 5-10 
Spines of length” 4 
era Leyes i paenvehieleness, jt 1.2-4 1.5 1-2 
length, limits 30-159 30-145 60-165 
Anchor 
breadth, limits yp 20-120 25-118 48-154 
Proportion of limits 100: 63-106 55-83 63-105 
anchor-length to — 
anchor-breadth average 100: 71.8 70.4 83 
Proportion of ey m 
anchor-length to limits 1: 2-2.4 2.2-2.4 2.2-2.4 
total length of the 
whole spicule | average Li: | 2.3 2.3 2.3 
1 When there oe ipo eine numbers in this zone it indicates that the length frequency-curve 
pertaining to the spicules of the variety or form has more pronounced elevations than one; in these the 
serrated amphidiscs do not appear to be biometrically homogeneous groups. 
