80 
CALYCOSILVA CANTHARELLUS. 
300-700 n, 16-47 /j thick, usually 19-32 n at the base, and on the whole conic. 
They taper gradually to the rounded end, which is 1-11 n thick, usually 2-4 /x. 
In two belt-like regions, one a short distance from the base and the other a short 
distance from the end, each lateral ray usually bears small, low spines, the spines 
of the proximal belt being larger and more numerous than those of the distal 
belt. The base, the middle, and the end of the lateral ray are usually smooth. 
The angles between the lateral rays are always nearly 90°. In this respect 
the crosses formed by them are regular. The length of the lateral rays of the 
same spicule is, however, by no means the same. In this respect the crosses are 
irregular. Among all the many pentactines I measured I found not one with 
equally long lateral rays. The difference in the length of the longest and short- 
est lateral ray of the same spicule amounts to 20-320 m- 
The apical (proximal) ray is similar to the lateral rays in shape, but very 
variable in length, 0.15-1.37 mm. long, and at its base usually somewhat thicker 
than the lateral rays. In most of the pentactines the proximal ray is well- 
developed and longer, in some reduced, as long as or shorter than the lateral 
rays. Some of these reduced proximal rays are truncate at the end as much as 
15 m thick. A correlation between this occasionally occurring reduction of the 
proximal ray and the development of the lateral rays does not seem to exist. 
The influences (obstacles) which prevent the silicoblasts building the former 
from properly executing their task of producing a proximal ray of normal length, 
do not appear to affect in any way those building the latter. 
A crowding of the spines is observed in the reduced apicals of the pentactines 
similar to that in the reduced hexactine rays, described above; it is not, however, 
so marked. The cause of this crowding is doubtless in both the same. 
The lateral rays of the hypodermal pentactines of the stalk (Plate 6, figs. 9-12, 
13a) are 230-520 m long and at the base 17-42 ^ thick, usually 18-32 m- They 
are conic, have blunt ends, and are either quite smooth or provided only with 
very small spines. The crosses formed by them are, like those of the pentac- 
tines of the body, regular in respect to the angles between the rays, which are 
always about 90°, but irregular in respect to their length, which always differs 
more or less. The difference between the length of the longest and shortest 
lateral ray of the same spicule is in these pentactines 10-80 /d. The apical (proxi- 
mal) ray is similar to the laterals in shape and usually about as long or only a 
little longer. 
As mentioned above there are two kinds of pinules ; pinules with properly 
developed proximal and apical rays, and pinules with such rays rudimentary and 
not at all, or but slightly, connected by intermediate forms. Both kinds occur 
