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



spaced, papilliform granules, and the prominent " dorsal " spines on the supero-marginal 

 plates are not yet developed. The infero-marginal plates are covered with spiniform 

 granules or thornlets longer and more pointed than those on the supero-marginal plates. 

 There is a distinct though extremely minute lateral spine, and one or two of the thornlets 

 near its base are slightly larger than the rest, especially on the outer part of the ray. 



The adambulacral plates, which are long and narrow, have their generic character 

 clearly presented. There is a straight furrow series of five or six short, cylindrical, 

 obtusely tipped spinelets, and behind these a secondary series of four or five similar and 

 equal-sized spinelets. This uniformity in size and character is a very interesting and 

 noteworthy feature in the young form. No other spinelets or granules are present on 

 these plates. Several well-formed large pedicellarise occur in each of the actinal inter- 

 radial areas, but I have found none elsewhere upon this young example. The paxillse 

 of the abactinal area have already more or less of the papillose character of the adult. 



Locality. — Station 44. Off the coast of North America, east of Maryland. May 2, 

 1873. Lat. 37° 25' 0" N, long. 71° 40' 0" W. Depth 1700 fathoms. Blue mud. 

 Bottom temperature 36°'2 Fahr. ; surface temperature 56°"5 Fahr. 



Remarks. — This variety resembles the type more nearly than the variety gracilis 

 does. The wide separation of the geographical positions of the type and its two varieties 

 is of the greatest interest, and bears evidence to the enormous range of the Dy taster cxilis 

 form, and of the comparatively small amount of variation exhibited by this type in what 

 may well be spoken of as extreme limits of position. The type comes from the Pacific, 

 off the western coast of South America, the nearly allied variety carinata from the North 

 Atlantic, off the eastern coast of the United States of America, whilst the more divergent 

 variety — if, indeed, it be not a distinct species — was dredged in the South Atlantic, 

 westward of Tristan da Cunha. 



3. Dytaster madrcporifer, n. sp. (PI. III. figs 3 and 4 ; PL XXXII. figs. 5 and 6). 



Pays five. P = 113 mm.; r = 18 mm. B = 6'25 r. Breadth of a ray near the base 

 (between the second and third supero-marginal plates), 14 mm. 



Pays elongate, narrow, and tapering, of massive construction, subrigid, or only with 

 very slight flexibility, perfectly rectangular in section, with rather high, vertical, square- 

 cut lateral walls. Interbrachial arcs very wide and flatly rounded. Disk small. Abactinal 

 surface of disk more or less inflated, subcarinate along the median line of the rays. 

 Actinal surface of the disk prominent and tubercular at the mouth-angles, but flat and 

 level externally and along the rays, forming with the lateral walls a sharp angle. 



The abactinal surface of the disk and rays is covered with small closely crowded pseudo- 

 paxillse, which consist of four to seven small, uniform, papilliform spinelets, cylindrical, 

 and obtusely tipped, borne on small, irregularly subcircular, squamiform bases. All are so 

 short, uniform, and closely placed, that it is almost impossible to distinguish the individual 



