208 THE VOYAGE OF H.M.S. CHALLENGER. 



SO thickly beset with rather long, narrow spines, diverging obliquely outwards, that a 

 somewhat bushy appearance results (PI. XXX. fig. 16). An essentially different appear- 

 ance is presented by the pinuli which lie on the funnel-shaped concave upper surface, in 

 the strands of the sieve. The basal rays are here narrower and longer ; the weakly 

 developed distal ray has a decidedly greater length — 0'8 mm., and bears only a small 

 number of short ap250sed spines (PI. XXX. fig. 17). On the inner surface of the gastral 

 cavity and wider efferent canals, a special gastral or canalicular skeleton occurs. This 

 consists of moderately large, smooth, simple ox\i:)entacts, with the four transverse 

 rays inserted on the gastral or canalicular membrane, and sparsely furnished with 

 slim autogastral pinuli of various sizes. The four straight basal rays of the latter are 

 rather long and thin, and gradually pointed ; the distal ray is slim and beset with short, 

 somewhat apposed, lateral spines. 



Among the dermal amphidiscs there frequently occurs a large, comparatively broad 

 form (0'5 mm. long by 0'2 mm. broad), with short, much arched umbels, and eight 

 broad lancet-shaped umbel rays. The strongly developed axial rod is for the most 

 part smooth, but generally exhibits at the middle point four cruciately disposed^ 

 rounded tubercles, — the remnants of the four abortive transverse rays. In the superior 

 sieve-plate these large broad amphidiscs which occur all over in the external skins are, 

 curiously enough, absent. On the other hand, medium-sized (0"3 mm.) amphidiscs of 

 another form occur, with narrow, much arched, eight-rayed umbels, which occupy more 

 than a third of the total length, sometimes almost meeting in the middle. The slim axial 

 rod is beset with tubercles (PI. XXX. fig. 11). Besides these, somewhat smaller and 

 narrower amphidiscs, with eight medium-sized nmbel rays occasionally occur, and in 

 great numbers the decidedly smaller forms with short, broadly-arched many-rayed umbels 

 which occurred so abundantly in the external skin (PL XXX. fig. 13).^ 



In the basal pad the familiar strongly-developed six- to two-rayed spicules occur 

 abundantly. Their rounded ends are covered with tubercles, while the proximal main 

 portion of the ray is smooth. The bundle of needles in the basal tuft is unfortunately 

 torn away. At the inferior extremity of the body one can see the distinct defect left by 

 their removal. 



Hyalonema poculum, n. sp. (PI. XXXIII. figs. 1-7). 



In the neighbourhood of the island of Juan Fernandez, west of Valparaiso (lat. 

 33° 42' S., long. 78° 18' W., Station 300), a cup-shaped Hyalonema was dredged from 

 a Globigerina ooze bottom at a depth of 1375 fathoms. The inferior extremity and 

 tuft of basal needles is torn away. The upper funnel-shaped concave end of the 

 comparatively thin- walled cup has a transverse diameter of about 5 cm., while the lower 

 I Too few rays have been represented in PI. XXX. fig. 13. There are from thirteen to sixteen. 



