186 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



sometimes to a single series, rather widely spaced on edge of plate*, 

 and the general surface of the marginals, beyond the basal fourth of 

 ray, is bare, or has only a very few widely scattered spinelets. R= 

 about 95 mm., r=11.5 mm.; R=about 8 r; rays narrow, long with 

 a very attenuate distal portion; 15.5 or 16 adambulacrals to first 10 

 inferomarginals. 



Description. — Beyond the fifth superomarginal, the central spine 

 of the abactinal plates (which is generally absent from the lateral 

 portions of area) is accompanied by 3 to 5 — very rarely more — small 

 spinelets, or by only 1 or 2. Sometimes the spinelets are entirely 

 lacking, especially on the distal half of the ray. In some specimens 

 the reduction is more accentuated. The other plates bear 1 to 5 

 (sometimes 0) inconspicuous spinelets. The average large paxillae 

 of disk and basal portion of ray bear 5 to 15 granuliform spinelets 

 in a single circle around the central spine. A variable, but usually 

 small, number of fasciculate and pectinate pedicellariae, with 2 to 8 

 robust jaws, are scattered over disk ami proximal half of ray. 



Marginal spines stout. With the exception of the first 2 to 4 

 plates, the spinelets are relatively few and found mostly around 

 the borders, sometimes fairly widely spaced and in a single series, 

 with a few spinelets widely scattered over the general surface. The 

 marginal series may even not be complete, or along the transverse 

 borders 2 or even 3 series, usually irregular, may be present, with 

 only 1 on the longitudinal margin. As a consequence most of the 

 surface of the marginal plates is bare, and more of the surface of 

 the superomarginals is unencumbered than of the inferomarginals. 

 The second inferomarginal spine is stout, and on the first 2 or 3 

 plates a third is often present (as in miniicus). Certain supero- 

 marginals may have 2 spines, and inferomarginals 2 primary spines 

 and 2 secondary, or 1 primary and 3 unequal secondary. These 

 plates are irregular or inconstant in occurrence. 



Adambulacrals with a salient furrow margin and T to 9 furrow 

 spines, very similar to the armature of the typical form. The sub- 

 ambulacral spine is rather stouter than usual in mimicus^ and distally 

 there is a second smaller one (as in mimicus) between the furrow 

 margin and the principal spine. The first 2 plates in 2 out of the 

 6 specimens have 2 subambulacrals. Mouth plates with 2 or 3 

 stout suborals and about 6 marginal spines, in addition to a series 

 of 6 along the margin of median suture. 



Pedicellariae abundant, and present: (1) Sparsely on the abactinal 

 surface (pectinate and fasciculate) ; (2) in variable numbers on 

 the suture separating the supero- and inferomarginal plates, both 

 interbrachially and along the ray, or interbrachially only (fascicu- 

 late) ; sometimes these occur near the upper edge of an inferomar- 

 ginal; (3) 1 to 3 pedicellariae near the inner edge of the infero- 



