86 HAWAIIAN AND OTHER PACIFIC ECHINI. 



The anibulacnil pores near the actinal system are somewhat crowded 

 together; the membrane of the sHght actinal cuts extends well up in the 

 angle between the ambulacral and interambulacral areas (PL 53, fig. 1). There 

 are from six to nine small but deep actinal sphseridial pits in the median 

 ambulacral zone. 



There are four anal plates, surrounded by a narrow raised ring formed 

 by the genitals (PI. 53, fig. 2). The genital pores are distal, placed close to 

 the outer angle of the genital plates ; the madreporic body is clearly indicated 

 by small pores. The genital plates, which are irregularly heptagonal, carry 

 scattered tubercles of the size of those of the abactinal interambulacral plates 

 (PI. 53, fig. 2). The ocular plates are pentagonal and are excluded from 

 the anal system. 



The actinal system is decagonal, slightly indented in the median ambulacral 

 line, and is closely covered with minute longitudinal plates, among which are 

 placed the five widely separated pairs of buccal plates with their minute 

 pores (PI. 53, fig. i). 



Coeiopleurus maculatus is a strikingly handsome species (PL 57, figs. Jt-6) 

 with its polished, bright pea-green piimary spines conspicuously spotted on 

 the upper side with scarlet red. The lower side is white, with somewhat 

 indistinct red markings, as though the spots on the upper side showed 

 through (PL 53, figs. 5, 6, 7). Towards the tip of the spine, on the upper 

 side, the red spots become confluent so that the distal part of the spine is 

 red for a greater or less distance, though it may be tipped with green or 

 white. The primary spines are sharply triangular, especially neAr the ba.se, 

 and are distinctly curved towai'ds the tip. The collar is short, rarely over 

 5 mm. in length, dull and usually rough, with four or five longitudinal series 

 of coarse granules, on each side. The small actinal primary spines are Hat 

 a!id smooth, pure white, with very conspicuous gray collars extending lialf 

 their length. The secondary spines are stout and blunt. In the largest 

 specimen of C. maculatus, measuring 37 mm. in diameter, the primary spines 

 are from three to three aiid a half times the diameter of the test. With tlie 

 additional material from Japan at our disposal we find that the dilTerent 

 species of this genus can at once be readily distinguished by the marking of 

 tlie abactinal interambulacral area, the coloration of the spines, and the length 

 of tlie collar, lu C. J^fuil/anli ihc primaries are green, marked with deep 

 ])uiple spots. The collar is S mm. long and llnely and luiiformly granular 

 (LI. 5o, ligs. ,s\ u). In C. maculatus the primaries are green, with the spots 



