AMBLYPNEUSTES PALLIDUS. 481 



plates ; these secondary tubercles are largest between the principal vertical row 

 and the poriferous zone, quite small towards the median line or wanting, leav- 

 ing the median interambulacral space nearly bare or Idled with minute dis- 

 tant granules. The ambulacral space is narrow, with narrow poriferous zones ; 

 pores arranged in short oblique arcs of three narrow pairs of pores. Adjacent 

 to the poriferous zone, in the median ambulacral sj^ace, there is a promi- 

 nent vertical row of primary tubercles closely packed, as large as the pri- 

 maries of the interambulacral space ; the median space is more or less bare ; 

 comparatively large secondaries form from one to two irregular vertical rows 

 next to the outer primary row. The general color of the test is light olive- 

 green, with darker zigzag lines parallel to the median sutures in both the 

 ambulacral and interambulacral areas ; these lines are especially distinct and 

 numerous near the abactinal pole, they diminish gradually in intensity and 

 number towards the actinostome. From the median line horizontal lines of 

 the same color extend sometimes along the sutures, and have a tendency to 

 form indistinct lozenge-shaped figures near the poriferous zone, on the outer 

 edge of the interambulacral area. The primary tubercles of both areas are 

 considerably larger immediately round the actinostome. A dark brown band 

 often extends from pole to pole on the inner side of the poriferous zone 

 adjoining the median ambulacral space. The spines are short, slender, 

 pointed, of a dark green color at base, tipped with red, violet, or orange. 

 The abactinal system is smaller than in A. griseus; the ocular plates excluded 

 from the anal system ; genital openings large, notched out of the plate at 

 the very extremity of the genital plates. Anal system moderately large ; 

 genital plates of uniform size. The minute miliaries and secondaries scat- 

 tered through the poriferous zones form an irregular vertical row. 



Amblypneustes pallidus 



! Echinus pallidus Lamk., 1816. 



\ Amblypneustes pallidus Val., 1846, Voyage Venus. 



A better series of specimens than now exists in any of our Museums 

 will, I think, show the identity of A. pallidus and A. formosus. The peculiar 

 pattern of coloration so remarkable in A. formosus, as well as the delicate 

 sculptures of the median ambulacral and interambulacral spaces, exists in 



