HYALONEMA (PRIONEMA) AGUJANUM. 261 
either parallel, or slightly convergent or divergent. The teeth have the usual 
T-shaped transverse section. Their upper (outer) band-shaped part arises 
from the margin of a transverse circular dise situated at the end of the shaft. 
The diameter of this disc is a little less than a third of the anchor-breadth. In 
apical views of the anchors, the basal parts of adjacent teeth appear connected 
by the interdental parts of this dise as by a web (Plate 77, fig. 10). The upper 
band-shaped part of the teeth is 22-27 » broad at the base and in the middle. 
It is attenuated distally and pointed at the end. The contour of the tip of the 
tooth has the shape of a gothic arch (Plate 73, figs. 1-3; Plate 77, fig. 9). 
The macramphidises have on the whole narrower anchors and attain a 
considerably larger size in var. tenuis, form A, than in var. tenuis, form B, and 
in var. lata. Their dimensions are as follows: — 
NORMAL MACRAMPHIDISCS. 
Hyalonema (Prionema) agujanum 
var. tenuis 
= — = var. lata. 
form A. | form B. 
limits 225-440 200-350 207-370 
Total Oe 
length most frequently 387 320 320 
about wu 
Shaft, thickness p» 20-27 18-22 19-25 
diameter yp 28-43 26 24-34 
Central difference between 
tyle diameter of tyle and 4-19 5 2-11 
adjacent parts of 
shaft py 
: —- 9 47 
Snitesior length yu 7 5-15 
central tyle| cal thickness 8-11 | 10 5-9 
| 
length, limits 63-110 | 55-83 | 65-95 
Anchor 
breadth, limits p 116-172 119-160 112-168 
| 
Proportion of limits 100 : 143-221 ees iid=236 155-211 
anchor-length to —— 
anchor-breadth. average 100: 169 | 196 186.8 
Proportion of 2 : | a = 
anchor-length to limits 1: 3.9-5.4 4.2-4.9 | 3.1-5 
total length of 
whole spicule average 1: 4.7 4.7 4.2 
