116 NATURAL HISTORY BULLETIN 



Cn^TASTER NODosus Perrier. 



Chcetaster nodosus Perrier, Arch. Zool. Exper., v, p. 250, 1876. Sladen, Voy. 



Chall., XXX, pp. 398, 399, 778, 1889. 

 Chcetaster longipes (pars) Sladen, op. cit., p. 399, 1889. 



Plate viii ; figures 1, 2. Plate xiii ; figures 4, 4a.. Details. 



Rays five, nearly terete, long, slender, regularly tapered to 

 unusually slender tips and bearing large, scattered, tubercular 

 plates. Disk small, margins rounded. Radii of one 10™°^ and 

 74"^^; ratio, 1:7.3; of another, 9°^°^ and 76°^; ratio, 1:8.5. 



The dorsal and lateral surfaces of the rays are covered with 

 eleven radial rows of plates, five on each side and one carinal or 

 median, the latter similar in size and form to those adjacent. 



The lower ones, on each side, are smaller and their rows cease 

 at about the middle of the rays ; near the tips there are but five 

 rows. These plates have an expanded base and an elevated cen- 

 tral portion, which is smaller, transversely elliptical, nearly flat 

 on the top, which is covered by numerous small, slender and deli- 

 cate hyaline spinules; those around the margin are longer, 

 very slender and when perfect interlock across the spaces 

 intervening between the plates. They break off easily at the 

 base and then the plates appear granulated. 



The larger tubercle-like plates are often three to five times 

 larger than the others, and much more elevated ; they are round 

 or elliptical, convex, and covered with very numerous small 

 slender, rough spinules, those on the middle shorter. These 

 large nodular plates are irregularly distributed and differ in 

 number on the several rays; the number is often twenty to 

 twenty-five. They occur both on the median and lateral radial 

 rows of plates, but not on the disk in our examples. 



Papular pores of rather large size occur singly, in rows be- 

 tween all the dorsal and dorso-lateral rows of plates except next 

 the marginals. There are about two to each plate. 



The two regular rows of marginal plates are situated well 

 down on the ventral side. They are larger than the adjacent 

 lateral plates, thick, transversally oblong proximally, becoming 

 squarish and then rounded distally, convex and covered like the 

 dorsals with very numerous slender, minute, rough spinules, 



