STRONGYLOCENTROTUS PULCHELLUS. 357 



I and V are broadly insert (PI. 98, fig. 2) and the large suranal carries a well- 

 developed tubercle. The anus is decidedly excentric near ocular I. The madre- 

 poric genital is somewhat swollen and is much larger than any of the others. 

 All five carry tubercles, 2 or 3 on the proximal margin of each plate. — The 

 buccal plates (PI. 98, fig. 1) are of moderate size and are well spaced. Proximal 

 to them the membrane is thickly covered with small plates but distally these 

 become more and more scattered and a considerable part of the membrane is 

 perfectly bare. The gill-cuts are well defined but are neither narrow nor deep. 

 The primary spines are about 3 mm. long, stouter, and distinctly longer than 

 the secondaries. The test is very light purplish, noticeably darker abactinally, 

 particularly on the median interambulacral areas; on and around the abactinal 

 system there is a very evident greenish tinge. The primary spines are light 

 purple rather abruptly tipped with whitish. The smaller spines are much lighter. 



In the smaller specimen, there are only 9 interambulacral and 10 ambulacral 

 plates in each column. The arcs of pores contain only 4 pairs from the ambitus 

 adorally but 5 aborally. The arcs are not so clearly divided into an inner pair 

 and an outer trio by a small tubercle as in the larger specimen. Ocular V is 

 wholly exsert and a genital pore is visible only in genital 1. The primary spines 

 are purplish only at base and the terminal part is light greenish. 



The pedicellarise of pulchellus are quite characteristic, particularly the globif- 

 erous, the valves of which (PI. 94, figs. 24, 25) are only about .50 mm. long; 

 the base of the valves is .27 or .28 mm. wide and the terminal tooth is about 

 .20 mm. long. These pedicellarise are common and the stalks are about twice as 

 long as the head. The ophicephalous pedicellarise have valves about .20-.35 mm. 

 in length, besides the loop which is .03-. 12 mm. more; the valves a:e somewhat 

 constricted at base of blade, but not greatly so. The tridentate seem to be quite 

 rare; they have straight, narrow valves (PI. 94, fig. 26) only about half a milli- 

 meter long, and more or less in contact throughout. The triphijUous have the 

 valves about .12 mm. long and the truncate tip of the blade is about .09 or .10 

 mm. wide. The sphseridia (PI. 94, fig. 27) are fairly numerous and seem to be 

 rather elongated; they measure about .20 mm. in length but the width is scarcely 

 half as much. Spicules are scarce in the pedicels; they are C-shaped with the 

 ends branched. 



While this species is certainly nearly related to intermedius and drobachiensis, 

 the globiferous pedicellarise are sufficient to distinguish it from those or any 

 other species. 



It was taken by the ''Albatross" only at the two following stations: — 



