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



Width of arm close to disk 2 mm. Four or five small, conical, widely separated mouth 

 papilhe on each side, and three larger at apex of jaw. Mouth shield very large, long penta- 

 gonal, with an obtuse angle inward much wider without than within ; outer lateral corners 

 rounded ; length to breadth 2"7 : 2 - 3. Side mouth shields pointed oval, small, meeting 

 widely within. First under arm plate triangular, with sharp angle inward and outer 

 edge curved ; the rest within the disk four sided, with inner edge slightly wider than 

 outer, and lateral side a little re-enteringly curved ; beyond they gradually become wide 

 hexagonal. Side arm plates swollen, not meeting below till half a dozen joints beyond 

 the disk ; separated above by upper arm plates, which are much swollen, forming a high 

 ridge ; the first two or three nearly square with rounded corners ; those just beyond 

 rounded hexagonal ; and only near the middle of the arm do they become triangular, 

 with an angle within and outer edge curved. Disk thick and arched ; in centre of 

 upper surface a cluster of six large, round primary plates, separated by an irregular row 

 of smaller ; between inner ends of radial shields and in each interbrachial space a 

 conspicuous round plate ; on the margin are two plates connecting outer ends of genital 

 scales, and within these a large plate connecting outer ends of radial shields ; rest of 

 upper surface covered with small, swollen, rounded scales. Radial shields longer than 

 broad, rounded pear-seed shape, forming a well-marked notch over arm ; separated their 

 entire length by a single or double row of rounded scales; length to breadth 2.7:2. 

 The under interbrachial space is occupied by the large mouth shield, the lower edges of 

 the two small marginal plates, and the large genital scales, which are very narrow within, 

 widening without, as they extend upward over the arm, and bearing on their free edge 

 a close row of square, flat papillae, which begin at the third arm plate and maintain the 

 same shape in the arm comb. Three minute pointed arm spines, evenly spaced ; the 

 lowest next the tentacle scales. Tentacle pores oval and very large ; four short rounded 

 scales on each side of mouth tentacles ; the rest, within and well beyond the disk, have 

 four or more on the inner side, and one or two on the outer side. The entire surface is 

 microscopically tuberculous. Colour in alcohol, straw. 



Station 45.— May 3, 1873; lat. 38° 34' N., long. 72° 10' W. ; 1240 fathoms ; (young) ; 

 mud. Station 54.— May 27, 1873: lat. 34° 51' N., long. 63° 59' W. ; 2650 fathoms ; 

 grey ooze. Station 61.— June 17, 1873 ; lat. 34° 54' N., long. 56° 38' W. ; 2850 

 fathoms ; grey ooze. Station 133.— October 11, 1873 ; lat. 35° 41' S., long. 20° 55' W. ; 

 1900 fathoms ; globigerina ooze. 



Ophioglypha convexa, Lym. (PI. VI. figs. 13-15). 



Oxjlrioglyplia convexa, Lym., Bull. Mus. Comp. Zool., vol. v., part 7, p. 84, pi. iii. figs. 83, 84, 

 1878. 



Three small tapering arm spines. Disk covered above by a rosette of large, angular, 

 primary plates, radial shields, and a few large interbrachial plates. 



