CALYCOSILVA CANTHARELLUS. 
85 
long and generally strongly recurved, so that these end-rays become anchor- 
like. With the increase in size of the onychhexaster (length of the end-rays) the 
terminal spines become longer. In the largest onychhexasters they are 2-8 m 
long. At the same time they change their shape and their position relative to 
the end-ray from which they arise, generally being the more directed outward 
the longer the end-ray is. In the medium-sized onychhexasters (Plate 3 , figs. 
24, 25, 28-30) they are usually more or less vertical to the end-ray, their end 
being slightly bent inward (Plate 3 , figs. 28, 30) or outward (Plate 3 , fig. 29). 
In the large onychhexasters (Plate 3 , figs. 26, 27 ; Plate 4 , figs. 2-4, 13-19) they 
are generally directed obliquely outward. This clearly pronounced correlation 
between the length of the end-rays and the position of the terminal spines is very 
remarkable. 
The oxyhexasters (Plate 3 , figs. 4, 5; Plate 4 , fig. 1) are not numerous and 
have been found only in C. c. vars. helix and megonychia. They measure in the 
former 90-94 n in total diameter, in the latter 100-133 m- From a centrum 
5-7 m in diameter arise four smooth main-rays, 2-6 m long, 2-2.5 n thick in the 
middle, and thickened at each end. The main-rays of the same spicule are 
equal and their axes enclose angles of 90°. Each main-ray bears two to four 
end-rays, 40-60 n long and 1.5-2 n thick at the base. The end-rays arise steeply 
from the main-rays.. Their proximal end is curved inwards, towards the con- 
tinuation of the axis of the main-ray to which they belong. Their distal and 
middle-parts are nearly straight. The chords of opposite end-rays of the same 
main-ray enclose angles of about 70°. The end-rays bear along their length a 
few very small spines, are conic, and taper gradually to a fine point. 
This description shows that these oxyhexasters are very similar to the largest 
onychhexasters and distinguished from them only by the tips of their end-rays 
being destitute of terminal spines. In some hexasters (Plate 4 , fig. 1), similar 
in every other respect to the oxyhexasters above described, a slight angular 
bend is to be noticed 4-8 /x below the tip in one or more of the end-rays. In 
others again (Plate 4 , figs. 16-18) this angular bend is more pronounced, the bent 
end-part diverging strongly from the continuation of the middle-part of the 
end-ray. In others again only some of the end-rays are simply pointed, the 
others bearing terminal spines, similar to those of the large onychhexasters. 
From these observations I conclude that the oxyhexasters above described 
are to be considered as onychhexaster-derivates. I think their appropriate 
place is in a continuation of the onychhexaster-series beyond the end represented 
by the large ones with long end-rays and outward-directed terminal spines. 
