182 



THE OPIIIUKIDiE. 



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slightly concave; their outer end is a little thickened; almost equally broad 



and long. 



Disk covered with very small scales^ which are scarcely seen beneath the 



covering of spines. These are of two sorts (Fig. 4, a, b) ; short, thick, 



smooth ones, which end usually in three thorns, c. 0.1 mm. long (a little 



shorter on the central part of the disk than towards the margin), and long, 



slender ones, c. 1 mm. long, feebly thorny in their whole length, ending in 



few small close set thorns. The radial shields are very large, 



some 



triangular, with outer edge slightly curved, the other sides straight ; they 

 just meet without, and the corners are here a little knotted. Their width 

 is two thirds of their length, which is almost the same as the radius of the 

 disk; they are without spines. The ventral side of the disk is naked on the 

 inner part ; along the margin there is a rather broad band of small scales, 

 covered with spines of the small sort only. The margin of the disk not 

 produced in the interbrachial spaces. 



Five-six slender, translucent, serrated arm-spines, increasing in length 

 towards the dorsal side; the lower one is only half as long, the upper almost 

 three times as long as an arm-joint; sometimes, however, the uppermost 

 one is much shorter, the next two then arc the longest. From the fifth or 

 sixth joint the lower arm-spine becomes hook-shaped, with 2 to 3 thorns. 

 One small tentacle scale, except at the first pair of pores, which has none. 



Color in alcohol : white, with a slight purphsh tint, especially on the 



radial shields. 



Four specimens from Station 3405, 53 f. ; one of these has six arms. 



60. Ophiomyxa panamensis n. sp 



Plate VII. Figs. 1-3. 



Diameter of disk, 14 mm. ; width of arm close to disk, 3 ram. ; length of 

 arms about six times the diameter of disk. Four mouth papilla) on each side 

 of mouth angle, that on the apex a little larger than the rest ; they are finely 

 and irregularly serrate, but they have no transparent band along the margin 

 as in other OpUomyxa species. Below the first mouth tentacle are three 

 spine-like papilla3. Mouth shield transversely oval, broader than long, with 

 a rather indistinct peak within. Side mouth shields not meeting within. 



First ventral plate rather large, six-sided, or with outer edge broadly 

 curved. The second is in contact with the first, those beyond separated by 



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