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



mouth angle seven papillae, whereof the lateral were bead-like and had not yet become 

 long and slender. 



Station 344. — April 3, 1876 ; off Ascension Island ; 430 fathoms ; hard ground. 



Ophiacantha longiclens, Lym. (PL XXV. figs. 7-9). 



Ophiacantha longidens, Lym., Bull. Mus. Comp. Zool., vol. v., part 7, p. 144, pi. x. fig. 274, 



1878. 



Disk closely set with slender stumps, each bearing a crown of three to five long 

 delicate thorns ; arm spines translucent and thorny ; seven long slender mouth papillae ; 

 tentacle scales spiniform. 



(Type specimen from Station Cebu, Philippines.) Diameter of disk 4 mm. Width 

 of arm without spines 1 mm. Seven mouth papillae to each angle, of which the lateral 

 are long, spine-like and blunt ; and the innermost one is of a blunt spearhead form, like 

 the four teeth above. Mouth shield small, wider than long, bounded by a curve without, 

 and an angle within. Side mouth shields small, narrow, meeting within. First under 

 arm plate small and rounded ; second of an irregular transverse diamond shape, wider 

 than long, having the lateral corners sharp, and a slight lobe without (fig. 7) ; 

 those immediately beyond are similar, having a wide axe shape, with a clean curve 

 without. Upper arm plates small, of a wide fan shape, with the angle inward, and 

 lateral corners sharp. Side arm plates rather large, meeting above and below, with a 

 well marked spine ridge. Disk round, slightly puffed, densely set with slender, minute 

 stumps, each bearing a crown of three to five long slender thorns. Scaling and radial 

 shields hidden, except the outer tips of the latter. Seven flattened, translucent, thorny, 

 rather blunt arm spines; lengths to that of an arm-joint, 2, 2, 1"7, 1*7, 1, 1, '8 : "7. 

 One spiniform tentacle scale. Colour in alcohol, above, mottled brown; below, white 

 with brown markings on arms. 



Cebu, Philippines ; 95 to 100 fathoms. 



Ophiacantha nodosa, Lym. (PL XX. figs. 1-4). 



Ophiacantha nodosa, Lym., Bull. Mus. Comp. Zool., vol. v., part 7, p. 144, pi. x. figs. 258-261, 

 187S. 



Six arms ; seven long mouth papillae to each angle ; disk closely set with coarse, stout 

 stumps, having thorny ends and sides. 



(Type specimen from Station 3.) Diameter of disk 7 mm. Width of arm without 

 spines 2"3 mm. Seven narrow mouth papillae, the outer one longest. Teeth long and 

 narrow, though stouter than mouth papillae. Mouth shield small pentagonal, with a 

 wide angle inward ; length to breadth, '7 : "7. Side mouth shields long, narrow, and 

 curved, meeting within and extending without much beyond the mouth shield. Under 



