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 pinules, 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 m long, usually 105-140 fi, and 

 at the base 8-18 ix thick, usually 10-12 ix. 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 ^ 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 ^i 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 ix long, usually 110-142 n, and 

 at the base 6.5-15 n thick, usually 8-10 n. 



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 ju thick at the base. Its proximal 

 part is smooth, its middle- and end-parts covered with short spines 10-17 n 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 



