CCELOPLEURUS MACULATUS. 85 



Cocloplntrus Maillanli. This identification is not correct, the specimens 

 alluded to belonging in part to a new species ■which we have called Coelo- 

 pleurus loiigicolUs (q. v.) (described and figured nnder the name of C Mail- 

 larcli on PI. VI of the " Challenger" Echini, and on PI. V, figs. 1, 2), and in 

 part to the species we have called Coelopleuriis maculcttus ("Challenger" 

 Echini, PI. V, fig. 3). The latter may be at once recognized by the peculiar 

 ornamentations of the median abactinal part of the interambulacral area 

 which we figure on PI. 53, figs. 2, 4, of this memoir; this, with tlie red and 

 green color of the primary spines, at once distinguishes it from all the other 

 species of Coelopleurus. 



The specimen figured on PI. 53, figs. 1, 2, measures 24 mm. in diameter 

 and 15 mm. in height; the actinal system is 10 mm. in diameter, the abac- 

 tinal system 5 mm., and the anal system 4 mm. The greatest width of the 

 interambulacral system is 8 mm., while the greatest width of the ambulacral 

 system is 6 mm. There are ten and ten primary ambulacral tubercles occupy- 

 ing the whole median ambulacral space ; the six at the ambitus are the 

 largest, and they diminish in size towards both the actinal and abactinal 

 systems. 



The pores are arranged close to the edge of the scrobicular area in irreg- 

 ular arcs of three pair.s to each plate. They are largest on both sides of the 

 ambitus (PI. 53, figs. 1-3). The primary tubercle occupies nearly the whole 

 of each plate with the exception of the small tubercles filling the median 

 ambulacral space. The interambulacral primaries extend only to the seventh 

 plate from the actinal system. Tubercles similar to those in the ambulacral 

 median area occupy the median interambulacral space actinally, and extend 

 in the outer angle of each plate between the primaries and the poriferous 

 zone. Above the primary tubercles the interambulacral plates are covered 

 on the outer sides with a coarse granulation, leaving a straight, narrow, 

 smooth median area ornamented with a bare S-shaped marking. The bare 

 space being whitish is very prominent, the granides which flank it being 

 dark violet in striking contrast. The appearance of this bare interam- 

 bulacral space (PI. 53, fig. 2 ; PI. V, fig. 3, " Challenger " Echini) is thus very 

 different from what it is in other species of the genus (see the corresponding 

 figures of Coelopkiirus floridanus A. Ag., " Blake " Echini, Pis. VII, figs, i, 3; 

 VIII, figs. 1, 4, 7, 10, 11, U, 15, 16; of Coelopleurus Maillardi A. Ag., 

 Michelin, Maillard's Bourbon, Ann. A., PI. XIV ; and of Coelopleurus lon(/icollis, 

 A. Ag. and CI. "Challenger" Echini, Pis. V, fig. 1; VI, figs. 1, 2, 6). 



