168 



THE OPIIIUTIID^E. 



46. OpMacantha inconspicua n. sp. 



Plate XV. Figs. 7-11 



Diameter of disk, 7 mm. ; width of arms close to disk, without spines, 

 2 mm. ; length of arms about six times the diameter of the disk. Three rather 

 broad conical mouth papilloi on each side of the mouth angle ; that on the 

 apex not much larger than the rest. Mouth shield broader than long, 

 triangular, with an obtuse inner angle, side corners rounded ; inner sides 

 concave, outer edge curved. Side mouth shields meeting within, equally 

 broad in their whole length, a little curved. 



First ventral plate six-sided 5 the second sometimes in contact with the 

 first, those beyond widely separated; scarcely as broad as long. They have 

 an obtuse angle within, outer edge strongly curved, sometimes with a 

 median cut or a little concave ; inner laterals almost straight, outer concave. 

 Side arm-plates with rather prominent spine-ridge ; there is a narrow, not 



^ 



very distinct, naked space separating those of each two adjoining joints. 

 Dorsal plates all more or less widely separated, with an angle within, and 

 outer edge curved; broader than long. Arms not knotted, the joints being 

 inconsiderably constricted. 



Disk covered with small grain-like stumps (Fig. 11, a-c), about 0.1-2 mm. 

 long, usually ending in three thorns, which are each provided with a pair o£ 

 smaller ones. In one specimen (Station 3357), there are a few spines of 

 another shape (Fig. 11, b) among the common ones. The scales of the disk 

 are seen beneath the stumps. On the under side of the disk the same 

 stumps are found, but much more sparingly. The radial shields appear 

 as long, rather elevated ribs or ridges, almost reaching the centre of the 

 disk; their outer end is uncovered, and they are widely separated from 



one another. 



Six smooth arm-spines, on the inner joints 7-8. On the second joint they 

 form an almost continuous series over the dorsal side of the arm, farther out 

 they are widely separated above, and finely arranged along the sides of the 

 arm, a little curved (Fig. 9). The upper one is short and slender, except 

 on the two inner joints, the next two are much the longest, as long as 

 two-three arm-joints; the three (four) lower ones are little longer than an 

 arm-joint. One large oval pointed tentacle scale. 



Color in alcohol : pale gray. 



1 



