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



appearance. Side arm plates swollen, and not meeting below for some distance beyond 

 disk. Upper arm plates broader than long, thick and swollen, with outer side curved 

 and longer than the inner, which is nearly straight ; lateral sides re-enteringly curved. 

 Beyond, they are bounded by a long curve within and a peak without. Disk smooth, 

 arched, and very thick, covered above with small thin plates, having a minutely tuber- 

 culous or crystalline appearance ; in the centre are six circular primary plates, separated 

 by others irregularly shaped and angular, which also fill the interbrachial spaces. Radial 

 shields small, short, and thick, rounded triangular, with an angle outward, separated their 

 entire length by a round plate Avithout and several smaller plates within. Interljrachial 

 space below chiefly covered by the great mouth shields, outside which are three or four 

 rows of small scales, and on either side a genital scale, bearing on the free edge broad, 

 square, close-set papillse, which become narrower where they form the arm comb, on the 

 broadened outer end of the genital scale. Three small sharp arm spines, one situated in 

 a notch well up on the outer edge of the side arm plate, the other two lower, near j unction 

 of side with under arm plate. Tentacle pores very large, transverse oval in shape ; on 

 those of the mouth tentacles four rounded scales on the under arm plate, and three on 

 the other side ; the other pores within disk have usually four on the inner side, and one 

 wide scale on the outer. Colour in alcohol, body grey, arms straw-colour. 



Station 157.— March 3, 1874; lat. 53° 55' S., long. 108° 35' E. ; 1950 fathoms; 

 diatom ooze. 



Ophioglypha racliata, Lym. (PI. VII. figs. 1-3). 



Ophioghjpha racliata, Lym., Bull. Mus. Comp. ZooL, vol v., part 7, p. 89, pi. iii. figs. 65, 66, 

 1878. 



Two minute arm spines. Mouth shield trefoil. Under arm plates axe shape. 

 Radial shields small and rounded. Disk high. Basal under arm plates about as long as 

 broad. Arms high and rounded. 



{Type specimen from Station 205.) Diameter of disk 8'5 mm. Length of arm 35'5 mm. 

 Width of arm close to disk 3 mm. Four or five wide, rectangular, closely-set mouth 

 papillae on either side, with three long and pointed at apex of jaw. Mouth shields large, 

 trefoil shape, with a pointed lobe inward. Side mouth shields very narrow, of even width 

 and meeting within. First under arm plate largest of all, triangular, with an angle within 

 and outer edge much curved ; the other plates are axe-shaped, with re-entering lateral sides 

 and curved outer side ; the first three touch each other. Side arm plates thick, swollen, 

 and minutely tuberculous, meeting on the under surface beyond the third plate. Upper 

 arm plates much swollen, the first two rounded hexagonal, those beyond rounded 

 triangular. Disk high and rounded, covered with fine overlapping scales, of which the 

 marginal are the largest. Radial shields small, broader than long, four-sided, with rounded 



