HYALONEMA (OONEMA) BIANCHORATUM PINULINA. 320 
inner contour (the inner margin of the keel) and the lateral margin, on the 
other hand, diverge from the shaft. 
In specimen a I found a remarkable abnormal small macramphidise (Plate 
85, fig. 8) 190 » long, with terminal anchors respectively 80 and 100 » long and 
about 100 broad. In this spicule each anchor is composed of two partly 
incomplete and somewhat irregular verticils of anchor-teeth, instead of a regu- 
lar single one. This duplication is much more pronounced in one (the upper one 
in the figure) than in the other terminal anchor. Some of the teeth belonging 
to the inner (supernumerary) verticils are nearly straight, extend obliquely 
backwards, and are widened at the end to irregularly oval terminal discs. The 
position of these terminal discs is such that if the whole amphidiscs were assumed 
to be enclosed in a tight-fitting ovoid mantle or shell, the outer faces of the 
terminal discs would come to lie exactly in the (inner) surface of such mantle 
or shell. This observation seems to me to be of similar import as the one on 
an abnormal amphidise found in Hyalonema (Prionema) agujanum var. tenuis 
(p. 262, Plate 75, figs. 35-37); both favor the view that each amphidisc is 
formed within a single ovoid cell. 
The chief dimensions of the large micramphidiscs are: — 
of specimen of specimen of both speci- 
a i) mens together 
limits 79-90 79-87 79-90 
Length «_, —-22 
most frequently about 85 82 84 
Shaft, thickness, limits yu 4 3) 55 3.5-4 
Gentral transverse diameter of tyle, limits p» 4 4 
uyle thereple thicker teanithe shaft by, Wits 0.5 0.5 
length, limits pu 26-35 26-29 26-35 
breadth, limits uw 23-40 23-25 23-40 
Terminal | proportion of anchor- | limits 100 to 80-114 83-88 80-114 
anchors |length to anchor-|——— 
breadth average 100 to 79 86.3 OW 2 
proportion of anchor- | limits 1: 2.4-3.2 
length to total length -————_——. 
of whole spicule average 1: 2.8 
In these amphidises the shaft is straight. The central tyle is not defined 
and passes gradually into the adjacent part of the shaft. Tyle and shaft are 
very spiny. 
