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



(Type specimen from Station 325.) Diameter of disk 9 mm. Width of arm close to 

 disk, without spines, 1*3 mm. Three stout, close-set papdlae on either side of the mouth 

 angle, and two large and much rounded at the apex ; of those on the sides the outermost 

 is largest. Mouth shields small, triangular, a little longer than wide, rounded on all sides 

 except within, where is a point. Side mouth shields large, broad without, tapering 

 inward where they just meet. First under arm plate very small ; those beyond are 

 broader than long, angular, and with re-entering curves on the sides where are the 

 tentacle pores ; still farther out they are triangular, with outer edge much curved, 

 and a truncated angle within. Side arm plates short, not much projecting, meeting 

 above beyond the first upper arm plate, and below beyond the seventh or eighth. 

 Upper arm plates slightly swollen, very short and wide, of a transverse oval shape, 

 and with a small longitudinal ridge. Disk flat and tolerably thick, covered with thin, 

 small, flat, overlapping scales, with one somewhat larger, rounded primary in the 

 centre ; about four scales in the length of 1 mm. Radial shields long and broad, 

 bluntly pointed within, nearly or quite separated their entire length by a narrow wedge 

 of scales. On the interbrachial spaces on the under surface the scaling is much finer 

 than that above, there being about fifteen in the length of 1 mm. Three tapering, rather 

 sharp arm spines, the upper one being shorter than the other two, and the middle one 

 much the stoutest, and swollen. One small longer than broad tentacle scale on the 

 brachial side of the tentacle pore ; a little way out on the arm there usually is no tentacle 

 scale. Colour in alcohol pale straw. 



Station 325.— March 2, 1876; lat. 36° 44' S., long. 46° 16' W. ; 2650 fathoms; 

 grey mud. 



Amphiura cernua, Lym. (PI. XVII. figs. 13-15). 



Amphiura cernua, Lym., Bull. Mus. Conip. Zool., vol. vi., part 2, p. 28, pL xii. figs. 

 323-325, 1879. 



Four mouth papillae on each side. One tentacle scale. Three arm spines, the 

 middle one swelled. Disk scales coarse ; all primary plates conspicuous. First under 

 arm plate wide and large. 



(Type specimen from Station 241.) Diameter of disk 57 mm. Length of arm 

 about 24 mm. Width close to disk, without spines "7 mm. Four mouth papillae on 

 each side, of which three are short and blunt (the inner one being more pointed), and 

 two at the apex of the mouth angle are larger and more swollen. Mouth shields small, 

 flat, triangular, with a blunt angle inward and outer edge curved. Side mouth shields 

 broad without, and tapering inward, where they just meet. Under arm plates large, 

 with a long angle within and slight re-entering curves on the lateral sides. Side arm 

 plates slightly swollen, meeting below some distance out on the arm, and above beyond 

 the first upper arm plate. Upper arm plates transverse oval, slightly swollen, with 



