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 n 

 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 shghtly 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 megomjchia. They measure in the 

 former 90-94 ix in total diameter, in the latter 100-133 n. From a centrum 

 5-7 n in diameter arise four smooth main-rays, 2-6 /x long, 2-2.5 ^ 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 fi tliick at the base. The end-rays arise steeply 

 from the main-rays. Their proximal end is curved inwai'ds, 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 m 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 theu" 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. 



