CALYCOSILVA CANTHARELLUS. 
77 
one end is considerably thickened to a more or less spherical tyle, 24-50 /x in 
transverse diameter. Only a few rhabds are smooth throughout. In most a 
spined zone, 10-90 n in extent, is observed at, or just below, the ends. In the 
terminally thickened tyle-ends, this spined zone is short and situated terminally, 
the spines being sometimes restricted to a small patch on the apex of the terminal 
tyle. Also in the cylindrical strongyle rhabd-termini the spines often extend 
quite to the end. In the tapering rhabd-termini, which are usually slightly thick- 
ened in a spindle-shaped manner just below the end, the extreme tip is usually 
quite smooth. In such rhabd-termini the smooth terminal zone is sometimes 
27 fi long, the spined zone appearing as a belt below the end. The spines are 
conic, simple, 1.5-4. 5 /x long, and crowded quite closely in the spined zones. 
Abnormal rhabds are rare. In one there were two distinct centres, 5 /x 
apart, each with a cross of rudimentary transverse axial threads and a tyle. 
In another, one end was abruptly bent. Several show short rudimentary branch- 
rays, each with an axial thread, at one end. 
Some rhabds are corroded and have partly lost one or more of the super- 
ficial silica-layers composing them. In one, which had lost a part of its outer- 
most layer, a perfectly regular spiral split, forming six close turns, traversed the 
part of its still remaining portion bordering on the line along which the rest had 
broken away. 
The rectangularly bent diactines (Plate 5, fig. 20) have been found only in 
C. c. var. helix, and here also they are very rare. The two actines are straight 
or slightly bent, perfectly smooth, 1.3-2. 3 mm. and more long and 32-35 n 
thick at the base. The angle enclosed by them is 89-99°. 
The large slender-rayed triactines (Plate 5, fig. 21) have been found only in 
C. c. var. megonychia, and here also they are very rare. Their rays are smooth 
and at the base about 24 /x thick. Two lie in a straight line, from which the third 
arises vertically. 
The hexadines (Plate 1, figs. 14-24; Plate 2, figs. 4, 6, 9, 11, 14-16) of 
the two varieties are similar in shape and size. They measure 0.9-3. 4 mm. in 
total diameter. Their rays are 0.16-2.2 mm. long, straight or slightly curved, 
very rarely angularly bent, and, on the whole, conic. At their base the rays are 
18-67 /x thick and, for a distance of 40-160 n, smooth. Farther on they are cov- 
ered with spines for a distance of 140-450 ix. In this spined region the rays are 
thicker than at their base, and attain a thickness of 22-75 /x. In the rays reduced 
in length the spiny region extends quite to the end. In the normal long rays a 
distal part of considerable length, which is either smooth throughout or provided 
