Verrill, Notes on Radiata. 303 



alone extending to tlie summit ; the outside one hardly reaching the 

 upper surface ; the second reaching about half way from the outer 

 curvature to the genit:il plates; the inner rows successively shorter 

 than the third. The tubercles in all the rows diminish rapidly on 

 the upper side, those of the third row less so than others ; naked 

 median space narrow, depressed, sutures cons})icuous. 



Genital plates large, the outer end subacute, projecting into the 

 interambulacral spaces. Ocular plates tridentate on the outer side, 

 usually only two of them touching the anal membrane. The anal 

 area is covered with irregular, unequal plates. The poriferous zones 

 are rather broad, the pores large, in oblique rows of three pairs, which 

 become more nearly transverse at the outer margin. Actinal cuts very 

 deep, with elevated callous margins, which, on the side next the inter- 

 ambulacra, are elevated and sharp, slightly re volute, and bounded 

 externally by a shallow groove. The spines are short and stout, on 

 the lower side numerous, blunt, and subequal ; on the upper side 

 shorter, more unequal, and not so numerous. The major pedicellarite in 

 this species are numerous, especially among the spines of the lower 

 side, and are I'emarkable for their great size, the heads often -13 long; 

 and 6-0 broad at base ; with a pedicel -3 or more long. The three 

 branches are slender, somewhat smaller just above the enlarged base. 

 Other short, thick, rounded, and very much smaller pedicellarire are 

 scattered among the spines, and there is a thick wreath of similar ones 

 around the mouth. The buccal membrane is covered with numerous 

 scattered scales, which become smaller and crowded, near the mouth. 



Color, in life, light purple or rose-color ; when dried or in alcohol 

 dull purplish white, the test sometimes dull greenish above. 



This species, which appears to be beyond question a true Lytechi- 

 nus* is allied to X. variegotus of the West Indies, but still more so 

 to L. Atlanticus A. Ag. of Bermuda. The latter differs, however, in 

 having very slender and longer spines, much smaller and more slender 

 pedicellaiiaB, more uniform tubercles on the upper side, narrower por- 

 iferous zones, shallower actinal cuts, a more elevated form, and deep 

 purple color. The specimens of this species Avere identified by Mr. 

 Agassiz as the Boletia rosea by direct comparison with his original 

 specimens. A comparison with the Psammechinus semituhercidatus 

 will, however, be necessary before it can be definitely ascertained 

 whether they be really distinct. 



* By more recent comparisons I have been led to consider it nearer Boletia pileolus 

 than liere indicated. Tt is very near, if not identical with B. dejxressus, figured in Voy. 

 Venus, PI. 3, fig. 7,— Reprint. 



Trans. Connecticut Acap., Vol. I. 39 June, 1867 



