476 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



to an area, small; pores very small. Carinal plates forming an 

 evenly rounded, prominent, carinal ridge, the general form of the 

 plates being square. The transverse sutures, which are arched, are 

 nearly straight, while either border of the proximal plates is shal- 

 lowly notched in the middle to accommodate a small papula, and 

 each of the four corners of the plate is rounded, on account of a 

 small adjacent papular pore. Beyond the basal third of the ray this 

 notch disappears, on account of the absence of the pore (the corner 

 pores persist irregularly far along ray) and the lateral borders of 

 the plate are slightly convex. Proximally there are two transverse 

 rows of lateral plates to each carinal, but the regularity is soon lost. 



Adjacent to the carinals is a series of small, flat, sunken adradials, 

 overlapped by the carinals and superomarginals, the widest being 

 about one-third the width of the carinals. Between these and the 

 adambulacrals are 6 series of regular broadly elliptical slightly 

 tumid plates, wider than long and forming also regular transverse 

 rows. The 2 upper series (the marginal plates) are not larger than 

 the others, except that the 2 most actinal series are more covered by 

 the overlapping of the adjacent plates above, and appear to be 

 smaller. Very small papulae occur at the junction of any 4 plates, 

 except adjacent to adambulacrals. The surface of the plates is 

 covered with short, pointed, papilliform spinelets spaced one-half 

 to two-thirds their length, and the inferomarginals, and the actinal 

 intermediate plates (proximally 5 rows in all) have a central ap- 

 pressed, slender, needlelike spine, which on the inferomarginals is 

 scarcely longer than the plate (and is sometimes obsolete), but in- 

 creases in size regularlj'^ toward the furrow, the lowermost spines 

 being 2 or 2^ plates long. Near the end of ray the superomarginals 

 have also a small central spine. There are many small 2- jawed 

 pedicellariae along the sutures between plates, especially near the 

 papulae. 



Prominent adambulacral plates with a transverse oblique series 

 of 5 prominent spines, and adorally to the outer 2, a second trans- 

 verse series of 2 much shorter spinelets. A similar additional 

 spinelet sometimes stands at the outer end of the first series. The 

 innermost spine, deep in the furrow, bears a saccular investment, with 

 upward of 20 small pedicellariae, while the next spine, directed 

 across furrow has at the middle or base a large pedicellaria, with 

 slightly curved jaws as long as or a little longer than the spine. 

 The nonprominent plates have on the actinal surface usually 5 spines, 

 in 2 transverse series, the aboral the larger and containing 3. In 

 the furrow, near the adoral margin, on a level with the second spine 

 of a prominent plate (that bearing a large pedicellaria) is a short 

 spine with a bunch of 6 or 8 small pedicellariae. Proximally, along 

 the suture between the adambulacral and intermediate plates is a 



