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



(Type specimen from Station 192.) Diameter of disk 11 mm. Length of arm 50 mm. 

 Width of arm near disk 3 mm. Twelve mouth papillae to each angle ; of these the outer- 

 most one on either side is wide, like a short spatula, and is plainly the scale of the mouth 

 tentacle ; the next four papillae are sharp and peg-like, the pair at apex of angle are 

 thickened and conical. Five fiat teeth, a little longer than wide, with a curved cutting 

 edge. Mouth shields long heart-shaped, or broad spearhead-shaped ; length to breadth, 

 1*5 : 1'2. Side mouth shields large and three-sided, wide without, tapering inward, 

 where they nearly or quite meet. First under arm plate small and wider than long ; 

 plates beyond, wide pentagonal, with outer side gently curved, laterals re-enteringly 

 curved, and inner angle so obtuse and rounded as to be almost a gentle curve. Side 

 arm plates barely meeting below, separated above, rising in a thick abrupt spine ridge. 

 Upper arm plates small, thick, and fan-shaped, with the angle inward. Disk thick and 

 puffed, covered above by an even granulation, nine or ten grains in the length of 1 mm. 

 On removing these, there is disclosed a smooth coat of very thin scales, about five in the 

 length of 1 mm., which cover the radial shields, except their outer ends ; interbrachial 

 spaces below without grains, and covered with scales still finer than those above. Seven 

 slender, much flattened arm spines, slightly rough on the edges ; the uppermost one 

 extremely long, sometimes equal to five arm joints, diminishing to the lowest, which is 

 longer than one joint. Two large, oblong, slightly pointed tentacle scales. Colour in 

 alcohol, pale brown above, much lighter below. 



Station 192.— September 26, 1874 ; lat. 5° 42' S., long. 132° 25' E. ; 129 fathoms ; 

 mud. 



Ophiacantha rosea, Lym. (PI. XXV. figs. 10-12). 



Ophiacantha rosea, Lym., Bull. Mus. Conip. Zool., voL v., part 7, p. 139, pL x. figs. 

 267, 268, 1878. 



Disk scales and radial shields hidden by a thick skin, which is closely beset with very 

 short, stout spines, which sometimes are no higher than grains. Eleven arm spines, 

 slightly rough under microscope. 



(Type specimen from Station 308.) Diameter of disk 17 mm. Length of arm, 

 68 mm. Width of arms without spines 4*5 mm. Mouth papillae irregular ; there are 

 usually five on the inner part of the angle, flattened and blunt ; and outside these, near 

 end of mouth slit, a group of from three to six irregular papillae, short and flattened. 

 Eight or nine teeth, shaped like blunt spear heads. Mouth shields and side mouth 

 shields closely joined and covered with thick skin, so that their outlines are not clear. 

 Under arm plates shield shaped, with an angle within, a curve without, and re-entering 

 curves on the lateral sides opposite the large tentacle scales. Upper arm plates with 

 distinct outlines, broad fan shaped, with a rounded or very obtuse angle inward. Side 

 arm plates, near base of arm, barely meeting above and below, and having a narrow 



