78 THE VOYAGE OF H.M.S. CHALLENGER, 



Ophioglypha nodosa, Lym., 111. Cat. Mus. Comp. Zool., No. i. p. 49, 1865. 



Ophiura nodosa, Ltk, Vid. Meddel., p. 6, Nov. 1854; Addit. ad Hist., part 1, p. 48, pi. ii. 

 fig. 9 a, b, 1858. 



Greenland; Labrador; 12 to 50 fathoms. 



Oiihiocten. 

 Ophiocten, Ltk., Vid. Meddel., 1854. 



Disk thick and circular, without notches where the arms join it ; partly covered by 

 primary plates and radial shields, between which are sometimes fine, close-set grains, or 

 small scales, covering the squamous coat ; on the interbrachial spaces below, a simple 

 squamous coat, without any covering of grains. A row of papillae, passing along the 

 genital openings and sometimes upwards, along the margin of the disk, over the arm. 

 Side arm plates meeting below but not above. The second mouth tentacle is enclosed 

 between the first under arm plate and the outer end of the side mouth shield. Teeth. 

 Mouth papillae. No tooth papillae. Two genital openings, beginning at the sides of the 

 mouth shields. 



In respect to radial shields, coarse disk plates, and form of mouth angles, this genus 

 resembles the typical Ophioglypha, but the whole structure is lighter and more slender. 

 The genital plates are long, slim and scarcely clubbed at their outer end, to which is 

 attached a short, thin, genital scale. The arm bones are wider than high and have, 

 above, a small process running forward. There is a small, but well-marked transverse 

 oval peristomial plate. 



See Plate XXXVIII. figs. 18-21. 



'&- 



Table of Species of Ophiocten. 



Eegion between primary plates, on back of disk, occupied by a close flat granula- -\ 



tion or minute scaling. Besides the double arm comb, the basal iipper arm \ Ophiocten sen'ceum. 

 plates have a row of papUlfe along their outer edge, . . . . J 



Similar to preceding, but upper arm plates have no papLUa3, . . . Ophiocten ahyssicolimi. 



hlodeii depressum. 



Scattered granules on the upper surface of disk. Arm comb continued by small ) , , . 

 " -^ ^ > OjJihio 



spines along margin of disk, ..... 



Arm comb as in Ophiocten sericeum. Primary plates rounded and conspicuous | ^ , . ^ 



,,.,.,, ' > Ophiocten cmntmum. 



and separated by imbricated scales, . . . . . . J 



Arm comb somewhat as in preceding. Upper arm spine as long as three joints; 1 ^ ; ■ . / / / 

 the two lowest as long as one joint, ...... J 



Comb only along genital openings. Primary plates small and round, . . Ophiocten umhratieiim. 



No arm comb. Disk covered with minute scales, among which a few small, widely \ q -i ■ f ij-j 

 separated primary plates, . . . . . . ■ j 



