EURETE ERECTUM. 129 



their arrangement become. The proximal ray is straight, or slightly curved, 

 and attenuated, proximally and medially very gradually, distally very abruptly 

 towards the pointed end. It is 160-235 m long, rarely as much as 290 n, and 

 8-13 M thick at the base. Its basal and middle-parts are smooth. Near the end 

 it bears small spines. The lateral rays are in the same spicule usually fairly 

 equal. They are straight or very sUghtly curved and generally not extended 

 in a plane, but just perceptibly bent downward towards the proximal ray. The 

 angles enclosed between their chords and the proximal ray are consequently 

 somewhat smaller than 90°, those between them and the distal ray somewhat 

 larger. Apart from this they are regularly arranged, their projections on a 

 plane vertical to the axis of the apical rays enclosing angles of 90° with each other. 

 The lateral rays are 187-240 m long, 10-15 m thick at the base, and slightly at- 

 tenuated to the rounded end. Their middle- and end-parts bear small and 

 pointed (Plate 30, figs. 1, 9) or large and blunt spines (Plate 30, fig. 2). The 

 number of these spines is never great and on the whole in inverse proportion to 

 their size. 



The gastral pinule-derivates are connected with the gastral pinules above 

 described by transitional forms, but these are remarkably rare. Most of them 

 are fairly regular pentactines with an apical knob, the reduced distal ray; some 

 are irregular. 



The regular pentactine-like gastral pinule-derivates (Plate 30, figs. 8, 13, 14). 

 The proximal ray is usually straight, 250-320 n long, and 13-16 n thick at the 

 base. In regard to shape and spinulation it resembles the proximal ray of the 

 gastral pinules above described. The reduced distal ray is a rounded apical 

 protuberance, usually 7-12 m high, 14-18 m broad, and beset with a few large 

 spines. The lateral rays of the same spicule may be fairly equal or very unequal. 

 In extreme cases the largest are 30% longer than the smallest. The lateral rays 

 are shghtly inchned toward the proximal ray and also a little curved in this 

 direction (concave to the proximal ray) ; sometimes they are curved also in a 

 transverse direction. The projections of their basal parts on a plane vertical to 

 the axis of the proximal ray, however, always enclose angles of 90° with each 

 other. The lateral rays are 200-328 m long, and 14-23 ^ thick at the base. 

 Distally they *aper gradually and they are, at the rounded end, 7-13 m thick. 

 They bear thick, usually quite blunt, vertically arising spines, 4-10 ^ long. In 

 the middle-part of the ray these spines are large and sparsely scattered; towards 

 the end they become smaller, particularly more slender, and more numerous, the 

 end itself often being quite crowded with spines. I had the impression some- 



