REPORT ON THE OPHIUROIDEA. 233 



Ophioscolex dentatus, Lym. (PI. XXIV. figs. 4-6). 



Ophioscolex dentatus, Lym., Bull. Mus. Comp. Zool.,vol. v., part 7, p. 157, pL vii. figs. 184-18G, 

 1878. 



Three or four short, blunt, flattened, arm spines. Numerous mouth papilla?, whereof 

 the outer are flat, spiniform. One tentacle scale. 



(Type specimen from Station 142.) Diameter of disk 15 mm. Length of arm about 

 55 mm. Width of arm, without spines, close to disk 27 mm. There are seven mouth 

 papilla? on each side of an angle and one small and pointed at apex of jaw ; the three 

 outer are flat, spiniform, and much the largest and longest. On removing the skin the 

 mouth shield is seen to be wide triangular, having an obtuse angle within and outer corners 

 rounded. Side mouth shields long, narrow, and meeting within. Arms covered by a 

 thick skin completely hiding the plates, which are obscurely indicated below by transverse 

 furrows. On removing the skin, the under arm plates appear longer than wide, with a 

 curve without and a re-entering curve within ; the side arm plates small and meeting 

 neither above nor below, while the upper plates are only indicated by thin films of slightly 

 calcified skin. Disk round and rather flat, covered with a soft naked skin variously 

 wrinkled above and below. Genital openings wide and long, extending from the mouth 

 shield to the edge of the disk. Three or four short, blunt, flattened arm spines, equally 

 spaced, about as long, as an arm joint ; the upper and undermost usually a little the 

 longest. One small rounded tentacle scale on the inner side of the pore. Colour in 

 alcohol, light grey. 



Station 142.— December 18, 1873 ; off Agulhas Bank ; lat. 35° 4' S., long. 18° 37' E. ; 

 150 fathoms ; sand. 



Ophioscolex tropicus, Lym. (PL XXIV. figs. 1-3). 



Ophioscolex tropicus, Lym., Bull. Mus. Comp. ZooL, vol. v., part 7, p. 157, pi. vii. figs. 190-192, 

 1878. 



Seventeen to nineteen small, short, pointed close-set mouth papillae, occupying the 

 entire margin of each mouth angle. "Whole animal covered by a thick skin, through 

 which appear the lower and side arm plates, the mouth shields, and (indistinctly) the 

 scaling of the lower interbrachial space. 



(Type specimen from Station 24.) Diameter of disk 8 mm. Width of arm close to 

 disk, without spines, 1"3 mm. Eight or nine short, close-set, rounded mouth papillae, 

 occupying the whole length of each side, and one larger and more pointed at apex of 

 jaw. Mouth shields much broader than long, in shape transverse oval ; length to breadth, 

 "6 : 1"2. Side mouth shields long, curved and narrow, broader without, tapering inward, 

 where they do not cpiite meet. First under arm plate very small, nearly square, the 

 others larger, long hexagonal, with outer side curved, lateral sides re-enteringly curved, 



