128 
EURETE ERECTUM. 
lie below the pinule-layer and their end-ray bunches do not, as a rule, protrude 
beyond the surface. They are not numerous. 
The gastral skeleton consists of hexactine pinnies, regular and irregular, 
derivates of such with reduced distal apical (pinule) ray, and scopules. The 
pinules and pinule-derivates are very numerous and irregularly intermingled. 
They form, like the corresponding dermal spicules, a continuous superficial layer. 
Their lateral rays (Plate 30 , figs. 12b, 15b, 17b; Plate 31 , fig. 24b) extend para- 
tangentially, their apical proximal and distal rays (Plate 30 , figs. 12h, 17h; 
Plate 31 , fig. 24h) radially. The gastral scopules are situated radially. Most 
of them protrude a considerable distance beyond the zone of the lateral pinule- 
rays, and the end-ray bunches of many lie at a considerably higher level than the 
tips of the distal pinule-rays. The gastral scopules are much more numerous 
than the dermal. 
The dermal pinules (Plate 30 , figs. 7a, d, 10a, d, 12a, d, 17a, d; Plate 31 , 
figs. 2-5, 22) have a straight distal ray, 85-145 n long, usually 105-140 n, and 
at the base 8-18 n thick, usually 10-12 m- This ray is thickened above in a 
club-shaped manner and rounded distally. Its proximal part is smooth, its 
(thickened) middle- and end-parts covered with large spines. The maximal 
thickness of the distal ray (together with the spines) is 30-50 n, usually 40-48 n- 
The proximal spines are 5-8 n long, and nearly vertical to the ray, directed only 
slightly upwards. Distally the spines increase in size and become more and 
more inclined towards the tip of the ray; those arising from its summit are 
parallel to its axis. Half way up the spines attain the largest size. Here they 
are 8-13 n long. The proximal ray is usually straight. In its basal and middle- 
parts it is attenuated only slightly, at the end abruptly, towards the pointed end, 
like a Roman sword. It bears small spines near the end. The other parts of it 
are smooth. The proximal ray is 78-222 n long, usually 110-200 n, and at the 
base 6-13.5 n thick, usually 7-11 /x. The lateral rays enclose angles of 90° with 
each other and are, in the same spicule, fairly equal. They are similar to the 
proximal ray in shape and spiculation, 108-152 ^ long, usually 110-142 n, and 
at the base 6.5-15 n thick, usually 8-10 /x. 
The gastral pinules (Plate 30 , figs. 1, 2, 9, 12h; Plate 31 , fig. 24h) have a 
straight distal ray, 70-130 n long, and 11-17 n thick at the base. Its proximal 
part is smooth, its middle- and end-parts covered with short spines 10-17 /x long. 
The number of these spines is variable and never great. Sometimes there are 
only a few. The spines point obliquely upward and are rather irregularly 
distributed. The fewer there are, the more marked does this irregularity of 
