132 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



terete upright spinelets, becoming slightly longer, sharper, and 

 slender-squamiform near the spines. Terminal plate slender, cylin- 

 drical, longer than wide, with a terminal spine longer than itself, 

 and on either side 2 shorter spines. 



Inferomarginal plates extending laterally slightly beyond the 

 superomarginals, very narrow, with a tumid outer end, as in oedi- 

 ylax. Except for the first 2 or 3 plates which are wider than long, 

 all the plates are either as wide as long (to about the middle of ray) 

 or narrower than long (outer part of ray). For this genus the in- 

 f eromarginals are very narrow, and form a narrow, slightly beveled, 

 border to actinal area. Lateral spines proximally 3 (with sometimes 

 a slenderer fourth spine at upper end of series) distally 2, slender, 

 slightly curved, appressed, the lowest the longest and equaling 2.5 

 to 2.75 plates in length, on proximal half of ray. On the distal mar- 

 gin of the narrow actinal face of plate 2 or 3 much smaller, very slen- 

 der spinules continue the lateral series. These become so small on 

 the outer third of ra}^ thaf they merge into the general spinulation, 

 and owing to the extreme narrowness of the plates, the lateral coiiib 

 occupies the whole width. The spinelets covering the outer or lateral 

 face of plate are like those of the superomarginals, only a little 

 longer, but actinally become coarser, sharper, and well spaced. 

 There may be on the proximal plates an enlarged spinule near the 

 adoral margin. 



Actinal interradial areas very small for the genus, the distance be- 

 tween outer end of mouth plates and the edge of first inferomarginal 

 plate being slightly less than the interradial dimension of the mouth 

 plates. The series between the 2 points mentioned contains 4 or 5 

 plates. Intermediate plates extending to twelfth inferomarginal or a 

 trifle less than half length of ray. These plates are spaced from one 

 another, beyond the second inferomarginal. The plates bear groups 

 of 6 or 8 slender, sharp, terete spinules, which, by reason of the in- 

 vestment, appear smaller near the base, and which are a little shorter 

 than the subambulacral spines. Several plates in the interradial 

 area, adjacent to adambulacrals, bear prominent fasciculate pedicel- 

 lariae with 4 to 6 jaws swollen at the base and tapering like the other 

 spinules, but the calcareous part in reality is very slender. 



Furrow spines 5, occasionally 6, long, slender, compressed, pointed, 

 membrane-invested and webbed at base, forming a regular comb with 

 a curved outer margin. The mesial spines are about as long, on the 

 proximal third of the ray, as the neighboring inferomarginal plate. 

 Subambulacral spines very slender, terete, but apparently thick 

 and swollen, owing to the translucent tissue investing them. There 

 are about 6 of these forming 2 series on the second and third plates, 

 then on the succeeding plates a single zig-zag series, and finally on 

 the outer half or two thirds of ray 2 more or less irregular series, 



