REPORT ON THE OPHIUROIDEA. 45 



arm plates, which are hexagonal, with lateral sides straight aud two outer angles nearly 

 blended in a curve. Disk smooth, covered with small irregular plates, but little swollen. 

 Radial shields pear-seed shape, somewhat overlapped by adjoining scales ; just touching 

 without, diverging within, where they are separated by two or three small plates. The 

 rest of the upper disk is occupied by numerous scales, among, and separated by which, 

 appears a central cluster of primary plates ; in the interbrachial spaces are usually one or 

 more larger plates near the margin of the disk. Genital scales very broad above and 

 without, where they carry an arm comb of fine spines, but buried by disk scales below 

 near the mouth shield ; along their lower free edge is a row of minute tooth-like papillae, 

 between the genital plates and outside the mouth shield. Interbrachial space below 

 covered by irregular overlapping scales. Three slender arm spines, the longest one nearly 

 as long as a joint, and situated near the junction of the side arm plate with the upper, 

 and two others similar but shorter near the junction of the side with the under arm plate. 

 Tentacle scales small, short, pointed, four or five on each side of mouth tentacle pore, 

 whence they diminish in number, till just beyend the disk, where there are two on the 

 inner side of each pore. Colour in alcohol, grey. 



It difi'ers from 0}Moglypha lepida and Ophioglyplia cequalis in the coarser disk 

 scales. With them it connects the stout deep-sea forms to those of shallow water, like 

 Ophioglypha alhida. 



Station 122.— September 10, 1873 ; lat. 9° 5' S. to 9° 10' S., long. 34° 49' W. to 

 34° 53' W. ; 350 fathoms ; mud. 



Ophioglypha cequalis, hym. (PL IV. figs. 14, 15). 



Ophioglypha cequalis, Lym., BuU. Mus. Comp. ZooL, vol. v., part 7, p. 72, pi. iiL figs. 74, 75. 



Four very short, peg-like arm spines, equally spaced. Disk thin, with rather delicate 

 scales. Arms slender. 



(Type specimen from Station 218.) Diameter of disk 10 mm. Width of arm close to 

 disk without spines 1 "7 mm. Four or five short, square, separated mouth papiUas on each 

 side, with one much larger and pointed at apex of jaw. Mouth shields broader than long, 

 with outer edge curved, a blunt angle inward and a slight notch in the lateral sides ; 

 length to breadth 1'3 : 2. Side mouth shields short and narrow, meeting within. First 

 under arm plate broad triangular, with outer edge curved and a blunt angle inward ; second 

 plate broader without than within, pentagonal, wdth an angle inward, outer edge sHghtly 

 curved, and lateral sides re-enteringly curved ; the rest are broader than long, rapidly 

 becoming smaller in size beyond the disk, where they acquire the shape of a transverse 

 oval, with a little peak within and a curve without. Side arm plates even and of a 

 tubular figure, slightly projecting at their outer edge, meeting widely below, separated 

 above at the basal joints by the upper arm plates, of which the first and second form a 

 wedge with a curved outer edge, filling the notch formed by the arm combs, and bearing 



