86 CALYCOSILVA CANTHARELLUS. 
It seems very probable that they have been produced by a further development 
of the onychhexasters in the direction of small forms with recurved terminal 
spines, or large forms with upward directed terminal spines. I think that the 
forms described above, in which the end-rays appear to be angularly bent near 
the end, have been developed out of large onychhexasters by a reduction of the 
number of the terminal spines to one, and by a further increase of the angle 
at which this single remaining spine arises from the end-ray. The bent terminal 
part which appears as the distal end of the ray is, according to this, not a part 
of the end-ray at all, but a terminal spine. When, by a further development 
in this direction and a further increase of the angle between the terminal spine 
and the end-ray, this angle becomes 180°, an apparently true oxyhexaster is the 
result. 
That the oxyhexasters are to be considered as such ultra-end forms of the 
onychhexaster series is corroborated by the fact that they are larger than the 
largest regular onychhexasters found in the same variety. 
In the not spirally twisted irregular onychhexasters (Plate 3, figs. 2, 3, 6, 7), 
which are very rare, the end-rays only or both the end- and the main-rays may 
be irregular. The onychhexaster (Plate 3, figs. 6, 7) is an example of the former 
case. In this spicule, which was found in C. c. var. simplex, the main-rays are 
regularly disposed, equal, abnormally stout, 7 4 long, and 5.4 thick. Each 
main-ray bears only one or two somewhat irregularly curved end-rays, which 
are also abnormally stout, being 2-3 » thick at the base. The terminal spines 
are 3 » long and recurved. The whole spicule measures 74 » in maximum diame- 
ter. The onychhexaster (Plate 3, figs. 2, 3) is an example of the latter case. 
In this spicule, which was found in C. c. var. helix, two opposite main-rays, lying 
in a line, are considerably longer than the other four, and the end-rays are not, 
as is invariably the case in the regular onychhexasters, arranged in a verticillate 
manner at the end of each main-ray, but arise from them at various points. 
The main-rays are 4 » thick, the end-rays basally 2». The terminal spines are 
irregularly disposed, and 3-5 » long. The whole spicule is 89 u long and 64 u 
broad. I consider these rare, not spirally twisted, irregular spicules as mere 
pathological abnormities. 
The helonychhexasters are onychhexasters in which most end-rays or all of 
them are spirally twisted. To this spiral twisting the name I have given these 
spicules refers. The helonychhexasters are quite abundant in C. c. var. heliz, 
but absent in the other two varieties. 
The helonychhexasters of C. c. var. helix (Plate 2, fig. 3b; Plate 3, figs. 8-20) 
