EEPORT ON THE OPHIUROIDEA. 31 



Ophiopleura. 



Ophiopleura, Danielssen, Magazin for Naturvid., 1877. 



Disk notched and covered with fine scales and radial shields, which arc widely 

 separated. Numerous mouth papillae on a prolonged mouth angle. The pores of the 

 second mouth tentacles are like slits, are surrounded by numerous scales and open 

 diagonally into the mouth slits. The jaw plate is set along its whole height with tooth 

 papillae. Two genital openings in each interbrachial space, midway between the mouth 

 shield and the disk margin. Numerous tentacle scales on the basal pores. Arm spines 

 minute. Side arm plates meeting below but not above. Upper arm plates wide. 



Species of Ophiopleura not herein described. 



Ophiopleura borealis, Danielssen, Magazin for Naturvid, p. 33 (of separate copy), 

 tab. v. figs. 1-4, 1877. 



63° 5' N., 30° K; 510 to 570 fathoms. 



Ophiopleura arctica, Duncan, Ann. Mag. Nat. Hist., vol. ii., part 9, p. 266, 1878. 



Liitkenia arctica, Duncan, Ann. Mag. Nat. Hist., vol. ii., part 8, p. 188, pL ix. figs. 1-7. 

 Discovery Bay. 



Ophiemus. 

 Ophiernus, Lym., Bull. Mus. Cornp. Zool., vol. v., part 7, 1878. 



Central portion of disk inside radial shields covered by a thick skin ; round the 

 margin a broad band of scaling, interrupted only by radial shields, and covering also the 

 lower interbrachial space, the whole more or less hidden by the skin. Eadial shields 

 naked. Teeth, and small, numerous, close-set mouth papillae. First under arm plate 

 rather large, and bearing some of the scales of the second pair of niouth tentacles. 

 Upper arm plates covering the whole width of arm. Small smooth arm spines, arranged 

 along outer edge of side arm plate. Two large, long genital openings in each inter- 

 brachial space. 



In the size and function of the first under arm plate, and in the size and shape of the 

 upper arm plates, this genus has a slight relation to Ophioghjpha. 



The disk scaling and skeleton are light and friable, except the marginal scales and 

 radial shields. In its centre, the covering of the upper disk has only a lime-crust, broken, 

 but not divided into regular plates and scales. Teeth large and thick. The peristomial 

 plate is in one piece and thin. The flattened genital plate has attached to its outer end, 

 just at the articulation with the short, circular, radial shield, a very thin scale. The arm 



