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



or four in each row. Three small peg-like arm spines about one-third as long as a joint. 

 Colour in alcohol, pale grey. 



I was unable to detect any genital openings. 



Station 171.— July 15, 1874 ; lat. 28° 33' S., long. 177° 50' W. ; 600 fathoms. 



Ophiomusium granosum, Lym. (PL I. figs. 10-12). 



Ophiomusium granosum, Lym., Bull. Mus. Comp. Zool., vol. v., part 7, p. US, pi. i. figs. 12, 13, 

 1878. 



Most of the lower interbrachial space outside the mouth shield is occupied by broad 

 genital scales and a great central plate. No under arm plates beyond the third. Five 

 short, sharp, well-marked arm spines. The great lower interbrachial plate is separated 

 by a square one from the mouth shield. Margin of disk set with small points. 



(Type specimen from Station 237.) Diameter of disk 10 mm. Width of arm, without 

 spines, close to disk 2 mm. Mouth papillae very closely soldered together, forming a ridge. 

 Mouth shields triangular, with an acute angle within, and the outer edge curved. They 

 bear minute spines. Side mouth shields long and narrow ; meeting within, where they 

 are narrowest. Genital scales large, angular, longer than wide. First under arm plate 

 semicircular ; second and third triangular, with an acute angle inward. Side arm plates 

 minutely tuberculous, meeting broadly above and below, and nearly covering the entire arm 

 beyond the disk. Upper arm plates minute, triangular, with acute angle inward. There 

 are no tentacle scales. Disk covered with closely soldered plates, having decided furrows 

 between them ; the microscopic tuberculation usual in the genus is very coarse, and rises 

 near edge of disk into small points. The margin is occupied by a large, angular, swollen 

 plate, covered with points, which connects the radial shields with the genital scales, and 

 is united to the mouth shield by a smaller rectangular plate, also carrying points. Radial 

 shields pear-seed shape, diverging inward, where they are separated by a triangular plate. 

 In centre of upper surface of disk is a large pentagonal primary plate, surrounded by five 

 others, quadrangular, and connected with the radial shields by five rudely triangular 

 pieces ; in each interbrachial space above are two quadrangular plates, besides that of the 

 margin. Arm spines five in number, occupying the whole edge of the side arm plates ; 

 they are short, rounded, and delicately tapering. Colour in alcohol, grey. 



Station 237.— June 17, 1875 ; lat, 34° 37' N., long. 140° 32' E. ; 1875 fathoms; mud. 



Ophiomusium pulclidlum, Wyv. Thorn. (PL III. figs. 1-3). 



Ophiomusium pulchdlum, Wyv. Thorn., Voy. " Chall.," Atlantic, vol. ii. p. 67, figs. 18, 19. 

 Lym., BulL Mus. Comp. Zool., vol. v., part 7, p. 118, pi. v. figs. 144, 145. 



Primary plates bearing a large central tubercle ; second pair of side arm plates wide, 



