Ef'HINUS MILIARIS. 495 



secondary tubercles, forming neither horizontal nor vertical rows, arranged 

 irregularly, the spaces closely filled with miliaries. The plates of the 

 poriferous zone are high, shagreened with miliary granulation ; pores far 

 apart, distant vertically. Spines are fine, short, thin, generally colored 

 greenish, with white or yellowish tips ; the actinal plates are irregular in out- 

 line, forming a perfect closely packed limestone pavement over the buccal 

 membrane. 



Mediterranean ; Cape Verde Islands. 



Echinus miliaiis 



'.Echinus miliaiis Mull., 1771, Kxorr, Delic. 



pi. xxr.f. n. 



This the best known species can be taken as standard for comparison. The 

 outline is more or less pentagonal according to age ; the test is thick, flat- 

 tened below, slightly conical above ; in younger specimens the outline is 

 more regular, and regularly arched. The median interambulacral spaces are 

 closely packed with tubercles of nearly uniform size, one tubercle for each 

 plate, forming the two principal vertical rows of tubercles, being slightly 

 larger ; the other tubercles are arranged in two parallel irregular rows 

 exterior to the poriferous zone, tapering to the apex, and one horizontal 

 row in the centre of plate, towards the median line ; the rest of the plate 

 is filled by parallel horizontal rows of minute secondaries, with uniform mil- 

 iaries. The median interambulacral line is slightly depressed in old speci- 

 mens. The ambulacral space has two exterior larger and two interior smaller 

 vertical rows of tubercles of about the size of the second size of tubercles 

 in the interambulacral space ; groups of small secondaries in the poriferous 

 zone form an irregular vertical line adjoining the large row of tubercles. 



Abactinal system large, compact ; ocular plates small, all excluded from 

 the anal system ; inadreporic body not greatly larger than the other plates. 

 Secondary tubercles on the anal edge of genital plates ; anal plates few in 

 number, smooth. Buccal membrane strongly imbricated, formed of long nar- 

 row limestone plates, closely packed together. Actinal system of moderate 

 size ; cuts slight. Spines short, moderately slender, of a greenish tinge, with 

 pink, grayish, or whitish tips. 



