NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 209 



Bathy metrical range, 70 to 440 fathoms. Temperature range, 56.3 

 to 41.8. Four specimens. 



These specimens range in size from 7 to 14 mm. across the disk. 

 The length of the disk spinules is very variable, as is the shape of the 

 adoral plates, and the number and length of the sharp, slender spinules 

 on the outer edge of the upper arm plates show great diversity; in the 

 smallest specimens, the latter are wanting. The largest specimen has 

 nine arm spines and the smallest has seven on the basal arm joints. 

 Koehler suggests that inutilis may be identical with gratiosa, one of 

 the Investigator species he described in 1897, and these Japanese speci- 

 mens incline me to think that this is probably so, but as I do not feel 

 sure of it, I prefer to use the name inutilis for them. 



OPHIACANTHA DIPLASIA, new species." 



Disk 23 mm. in diameter; arms about 150 mm. long. Disk covered 

 with coarse, nearly spherical granules, which are slightly elongated at 

 the interradial margins ; distal to each of the radial shields, which are 

 completely concealed, is a group of slender spines of various lengths 

 (these spines were not seen in any of the other specimens 

 examined, but all of them (16) were smaller than the type). Upper 

 arm plates rhombic, more or less overlapping at base of arm and in 

 contact far out toward the tip ; at base of arm they are rather wider 

 than long, but distally they become distinctly longer than wide; the 

 distal angle of each plate is rounded or truncate and in large speci- 

 mens, near the base of the arm, may carry one or more large granules 

 like those of the disk; these are particularly numerous and noticeable 

 in the type. Interbrachial spaces below more or less fully covered 

 by somewhat elongated, pointed granules. Genital slits large. Oral 

 shields variable, but wider than long and usually rhombic ; often pen- 

 tagonal, and not uncommonly with the distal part abruptly narrowed 

 into a sort of bridge between the shield and the interbrachial space. 

 Adoral plates remarkably variable; often short, moderately wide and 

 wholly proximal to the oral shield ; more commonly long and narrow, 

 with more or less of an intrusive branch between the oral shield and 

 first side arm plate; in the type, the adoral shields are distinctly 

 L-shaped and completely inclose the oral shield, save for a short distal 

 margin. Oral papillae numerous, five to seven on a side and one or 

 more at apex of jaw, besides (in the type) one or two extra ones 

 on the surface of either the adoral or the oral plate; they are long, 

 flattened, blunt, and subequal, or the outermost may be longer or 

 wider than the others; it is sometimes very long. First under arm 

 plate small, wider than long; succeeding plates squarish or by trun- 

 cation of one or more angles, pentagonal, hexagonal, heptagonal, and 



, signifying twice as many, in reference to the pair of tentacle scales. 

 34916 Bull. 751114 



