34 
HOLASCELLA TARAXACUM. 
its thickest point, which lies only a very short distance below the end, the distal 
ray is 16-60 u thick. The proximal and the lateral rays are often curved; the 
distal ray is straight. The proximal and lateral rays are smooth apart from their 
ends, which are often slightly spined. The basal part of the distal ray is smooth, 
or only slightly spined; its thickened end is covered with spines, situated very 
obliquely and directed upwards toward the tip of the ray. These spines are 
quite numerous and close together, have a maximum length of 5 ju, and are 
about 4 n thick. They appear as oval protuberances, the ends of which are 
drawn out to sharp and slender points. The tip of the ray is free from spines 
for a distance of about 10 In the distal rays of medium thickness the 
tip appears as a broad cone, in the very thick ones as a broad round dome. 
The proximal part of the axial thread of the distal ray is quite thin, its distal 
part thickened, and about 1.5 n broad. 
I have observed a few spicules in the spicule-preparations which also appear 
to be hypodermal or hypogastral hexactines, but which differ from the spicules 
above described by one, two, or even three of their lateral rays being thickened 
and spined like the distal ray. 
The smooth root-spicules are all broken off at the lower, distal end. The 
longest fragments measured were 150-160 mm. long. Proximally these spicules 
are gradually attenuated to a fine point. Their thickest portion is about 120 
mm. from the proximal end; here they are 100-340 n thick. 
The spined, anckor-like root-spicules (Plate 22 , figs. 26, 37; Plate 23 , figs. 
2, 3) are remarkably scarce. All those seen were broken so that I cannot give 
their length. To all appearance they are much shorter than the smooth root- 
spicules. Near their distal end these anchor-spicules are 12-17 n thick. The 
end itself is thickened to a terminal tyle, 48-56 n broad, 54-70 n long, and in 
shape like a blunt, inverted cone with convex sides or a rotation-paraboloid. 
From the shaft of the spicule and from the margin of the upper, basal face of the 
terminal tyle arise conic, obliquely situated, backwardly directed spines 7-17 n 
long. The axial cross (morphological centre) of the spicule lies in the terminal 
tyle (Plate 23 , figs. 2, 3). These spicules are not, like the similarly shaped 
anchors of the species of Holascus, diactines, but monactine tylostyles. 
Among the micro-oxyhexactines, -oxypentactines, and -oxytetractines ( staur - 
actines ) (Plate 22, figs. 20-25), the hexactine forms appear to be the most 
abundant. The rays of these spicules enclose angles of 90° with their neighbours 
and are equal in most of the hexactines and stauractines. In the pentactines 
and some of the hexactines (Plate 22, figs. 20, 21) a differentiation of the three 
