THE OPHIURIDiE. 



173 



1 



First ventral plate rather large, six-sided or almost round. Tlic second 

 is broadly in contact with the first, those beyond all widely separated^, with 

 an obtuse angle within. They have the outer edge curved, wuth a httle 

 median cut; inner and outer laterals almost straight, outer corners rounded. 

 They are about as long as broad; as a whole they ai-e smaller than common 

 in Ophlacantha. Side arm-plates with sphie-ridge rather prominent. The 

 dorsal plates rhomboidal or triangular, according to the more or less strong 

 carve of the outer edge ; inner angle broadly rounded, side corners sharp. 

 They are widely separated ; however the side arm-plates do not meet 

 above till towards the end of the arm, being separated by a naked space, 



w 



in which there may be small separate plates developed. The arms appear 

 somewhat knotted, the joints being a little constricted ; they are much 



rolled up in our specimens. 



The disk is wholly covered above and below by rather large grains, 

 which end in some, small thorns (Plate XVI. Fig. 10). Also on the first 

 arm-joint some such grains are found. The radial shields are wholly 



* 



covered, but ajjpear as elevated ridges. 



At their outer end there is a 



little space covered with naked skin. The inner end of the genital scales 



distinct. 



Seven-six short, rather thick, thorny arm-spines, the upper one the 

 longest, scarcely longer than an arm-joint, the lower one not half as long as 

 an arm-joint J farther out also the upper one becomes shorter. One very 

 small, spine-like tentacle scale, that at the first pore placed nearer to the 

 median line of the arm, a little apart from the pore. 



Color in alcohol : grayish. 



Several specimens from Stations 3353, 695 f. ; 3424, 676 f. ; and 



3425, 680 f. 



This species appears to be rather nearly related to 0. discoidca Lyni.^ 

 from which it is, however, easily distinguished. 



• \ 



51. Ophiacantha contigua n. sp 



Plate XVi. Fig. 12, Plate XVII. Figs. 7-9. 



Diameter of disk, 5 mm. ; width of arm close to disk, without spines, 

 1 mm. ; length of arms about five times the diameter of the disk. 4-5 more 

 or less conical mouth papilto on each side ; that on the apex not much larger 

 than the rest. Mouth shield cciually broad and long, triangular, with a lobe 



11 



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