g2 BULLETIN "6, UNITED STATES NATIONAL MUSEUM. 



sometimes seen, but the plates are not distinctly lobed as in ornatissimus. In these 

 lateral regular series two papulae occur between every two plates, each plate being 

 surrounded by sLx. On the disk the papulai are confmed to the interradial angles. 

 A very large" plate stands on the adcentral side of the madreporic body, and on 

 eithcr'side of tliis a slightly smaller one, while four others, much smaller, complete 



the circle. 



Supcromarginal plates forty-sLx or forty-seven from interradial line to extremity 

 of ray are wider than long, the length increasing, the width decreasing toward end 

 of ray; and they gradually encroach more and more onto abactinal surface as they 

 proceed along ray. Plates form an arched bevel to distal half of abactinal edge of 

 ray, and a rounded lateral margin to ray in proximal portion. Plates slightly tumid 

 along aboral edge, and covered with low granuliform spinelets squamiform in middle 

 of upper half, thence decreasmg in size and becoming slender toward margins of 

 plate. No enlarged spinelets or tubercles on any of the supcromarginal plates. 



Inferomarginals corresponding exactly to superomarginals, but not extending 

 laterally beyond them except a very little, sometimes, near end of ray. Armature 

 consists of a series of five or sLx slender, tapering, sharj), slightly curved spines and 

 spinelets along aboral edge of plate; of these, three stand on outer end of plate, form- 

 ing a triple scries all along margin of ray, the middle spine being longest of the 

 three and about equalmg in length the width of plate; on actinal surface two or 

 three spaced, sharp, slightly flattened, much shorter spines continue this series 

 to inner end of plate. Adorally to the three marginal spines and close to them, 

 four or five sharp, flattened spinules (shorter than inner spines of above series) 

 form an obhque row meeting the aboral series just below the inner spine of margmal 

 row (which is also set transversely oblique). There may be four spines in the mar- 

 ginal series, and usually on the first four plates the largest spine is broader, flattened 

 and lanceolate or oblong-lanceolate in shape. It is here only about one-haK as 

 long as width of plate. General surface of plates covered with flattened, roimd- 

 tipped, upright, papilliform spinelets, increasing slightly in size toward the aiixihary 

 lateral spinules. 



Adambulacral armature in three or four fairly regular longitudinal series. (1) 

 Furrow spines three, the central longest and saber-shaped when dry, the laterals 

 shorter and slender when drj^, but in life with more or less evident membranous expan- 

 sions at base, giving the spine a flattened appearance. (2) First actinal series consist- 

 ing of two or three slightl\- shorter spines, of which the aboral is very much the 

 stouter, being flattened with a rounded or tnmcate tip. The adoral spine is shorter 

 anrl when there are three in the series they are graduated in length. (3) On outer half 

 of plate are two to five shorter shghtly flattened spines either in an irregular group, 

 or farming a series of two or a series of three, with one out of line in addition, or 

 sometimes two series of two. In large specimens the armature is less regular. 

 Sometimes a series of two smaller spines is interpolated between the furrow series 

 and the first actinal, or again only one such spine. Irregularity is frequent on 

 plates near the mouth, but usually the larger flattened spine is recognizable on the 

 actinal surface. First adambulacral much compressed, the second less so; former 

 with a double transver.se series of closely appressed spines, about 30 in number. 



Combined mouth plates narrow with a crowded armature consisting of three 

 serif-. H marginal, rather high on side of furrow, an intermediate, and most con- 



