88 CALYCOSILVA CANTHARELLUS. 
twisted for a greater part of their length is much more irregular. Here the spines 
scattered along the length of the end-ray are not uniformly distributed and often 
restricted to its outer, convex side; they are also unequal in size, some of them 
attaining a very considerable length. Such end-rays usually have only one ter- 
minal spine, sometimes 6.5 1 in length, which is directed obliquely outward. 
The angle between this terminal spine and the adjoining part of the end-ray 
usually is rather obtuse and not infrequently becomes 180°. In this case the 
terminal spine appears as the tip of the end-ray, and the end-ray itself becomes 
simple, as in the oxyhexasters above described. 
Intermediate forms with somewhat curved but not properly spirally twisted 
end-rays, connecting the helonychhexasters with the regular onychhexasters, 
have occasionally been found, but they are exceedingly rare. 
Spicules twisted spirally like the helonychhexasters of C. c. var. helix have 
repeatedly been noticed in Hexactinellida. 
Oxyhexasters and oxyhexaster-derivates with a reduced number of spirally 
twisted rays have been found by F. E. Schulze in Holascus stellatus" Holascus 
ridleyi,? and Rhabdocalyptus mollis* and by Ijima in the last named species,* 
in Hyalascus giganteus* and in Staurocalyptus pleorhaphides.° 
_ Discohexasters with the verticils of end-rays twisted spirally round the 
continuations of the axis of the main-rays from which they arise, have been 
found by F. E. Schulze in Hertwigia falcifera,’ Rhabdopectella tintinnus,*® and 
Saccocalyx pedunculata °. 
Clavules with branch-rays twisted spirally round the shaft have been 
found by F. E. Schulze in Farrea convolvulus © and by Wilson in Farrea occa 
claviformis |. 
The spirally twisted oxyhexasters of Holascus stellatus, Holascus ridleyt, 
Rhabdocalyptus mollis, Hyalascus giganteus, and Staurocalyptus pleorhaphides 
are similar to ordinary, not twisted oxyhexasters occurring in the same sponge 
and more or less connected with them by intermediate forms. The same applies 
1 Ff. EB. Schulze. Rept. Voy. Challenger, 1887, 21, p. 86, pl. 14, figs. 10-12. 
2 F.H. Schulze. Loc. cit., p. 90, pl. 17, fig. 7. 
3 Ff. EH. Schulze. Loc. cit., p. 157, pl. 64, figs. 10, 11. 
47. Ijima. Studies on the Hexactinellida. IV. Journ. Coll.sci. Tokyo, 1904, 18, p. 266, pl. 20, fig. 9. 
5]. Ijima. Loc. cit., p. 106, pl. 8, fig. 16. 
87. Ijima. Loc. cit., p. 229, pl. 16, fig. 8. 
7 PF. EH. Schulze. Amerikanische Hexactinelliden, 1899, p. 23, taf. 3, fig. 8. 
8 F. E. Schulze. Rept. Voy. Challenger, 1887, 21, p. 108, pl. 12, fig. 8. 
°F, #E. Schulze. Hexactinelliden desjIndischen Oceanes. II. Abh. Akad. Berlin, 1895, 1896, p. 55, 
taf. 5, figs. 4, 9, 10. 
0 Ff, #. Schulze. Amerikanische Hexactinelliden, 1899, p. 72, taf. 16, figs. 1, 2. 
1 H. V. Wilson. Mem. M. C. Z., 1904, 30, p. 59, pl. 7, fig. 3. 
