614 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1885. 



Echinocyamus pusillus Van Ph. 



Oue living specimen from station 2352, 463 fathoms (10632); dead 

 specimens from station 2342, 201 fathoms (10631); station 2354, 130 

 fathoms, and station 2359, 231 fathoms (10623). 



Clypeaster Ravenellii A. Agassiz. 



Station 2312, 88 fathoms (10055) ; station 2313, 99 fathoms (10056) ; 

 station 2317, 45 fathoms (10075); station 2318, 45 fathoms (10643), one 

 young specimen ; station 2388, 35 f^ithoms (10054), a fine kirge series, 

 containing over one hundred specimens; station 2403, 88 fathoms 

 (10057); station 2404, 00 fathoms (10626, 10644), young and dead frag- 

 ments; station 2417, 95 fathoms (10058), ten specimens. 



The largest specimen collected measured about 135 millimeters in 

 diameter. This species was associated with Clypeaster suhdepressus at 

 stations 2317 and 2388. The majority of the specimens of G. subde- 

 'pressus obtained were of small to medium size, and rather shorter iu 

 proportion to the width than in the more typical specimens ; the width 

 was frequently nearly equal to the length. There is, however, no diffi- 

 cultj^ in distinguishing these two species, even in very young specimens. 

 In G. Ravenellii the length and width are always closely the same, ex- 

 cepting in abnormal specimens; the margins, iu the interambulacral 

 spaces, excepting in small specimens, are nearly always distinctly, and 

 sometimes quite strongly, incurved, and the entire margin is consider- 

 ably thickened. In some specimens of G. suhdepressus the margin 

 becomes slightly thickened, but never so much so as in C. Ravenellii. 



The entire median portion of the test of G. Ravenellii, on the abactinal 

 side, is greatly elevated, with rather abrupt though regularly arched 

 slopes, extending about to the outer ends of the ambulacral petals. The 

 petals are broadly open at their outer ends, and have the poriferous zones 

 nearly parallel along the outer two-thirds of their length. The granula- 

 tion of the test is much coarser than in G. suhdepressus, and the principal 

 granules much more widely separated. The coarse granulation of the 

 actinal surface approaches less closely to the ambulacral furrows, 

 which, especially in small specimens, are frequently bordered with 

 broad comparatively smooth areas, reaching to near the margins of the 

 test. The ambulacral turrows are deeper and broader. In nearly all 

 the living specimens which have been denuded, the sutures between 

 the plates on the abactinal surface are marked with purple, forming a 

 network distinctly outlining the coronal plates, especially toward the 

 margins. This color is sometimes continued over a portion of the 

 actinal surface. The color of both dried and alcoholic specimens is a 

 very bright greenish yellow, more or less uniform over both the upper 

 and lower surfa<ies. Large specimens are sometimes less brightly col- 

 ored than small ones. 



The color of most of the alcoholic si^ecimens of G. suhdepressus, not 

 denuded, was a dull grayish brown on the abactinal surface, the same 

 color also marking the interambulacral spaces on the actinal surface. 



