HELIOCIDARIS STENOPORA. 351 



Actinostome .30-.35 h. d.; pore-pairs mostly in arcs of 7, of which only the 



outer 3 or 4 form more or less vertical series above the ambitus. 

 Primary spines very dark (blackish, purplish, or brownish); test very flat 



actinally with poriferous areas more or less petaloid crassispina. 



Primary spines dull reddish or greenish, often with more or less of distal 

 half, violet; test not flattened actinally and poriferous areas not peta- 

 loid erythrogramma. 



Actinostome .35-.40 h. d.; pore-pairs mostly in arcs of 8 (occasionally 9), of 

 which the outer 4-6 are in more or less vertical series above the ambitus, so 



that the poriferous areas are very narrow stenopora. 



Pore-pairs 9 or often 10 in each arc tuberculata. 



Heliocidaris stenopora, 1 nom. nov. 



Toxocidaris mexicana A. Agassiz, 1863. Bull. M. C. Z., I, p. 22. NON Heliocidaris mexicana L. 

 Agassiz and Desor, 1846, Ann. Sci. Nat., (3), VI, p. 372. 



' Plates 95, figs. 18-22; 104, figs. 1-3; 110, figs. 4, 5. 



As this species appears to be rather rare, few specimens having found their 

 way into museums, it seems desirable to give figures of the specimen in the 

 M. C. Z. collection, which is almost certainly the type. Its measurements cor- 

 respond with those in the "Revision." All four kinds of the pedicellarise figured 

 were found on this specimen. The globiferous have valves about .45 mm. long 

 (PI. 95, fig. 18) with a prominent lateral tooth on the left side of the blade near 

 the tip (PI. 95, fig. 19). The ophicephalous have valves (PI. 95, fig. 20) of about 

 the same length, counting the "loop"; they are not constricted at the base of 

 the blade. The tridentate are also of about the same size, with rather wide, 

 somewhat curved blades (PI. 95, fig. 21). These three kinds of pedicellariae 

 are covered with a dark tissue, which makes them all look much alike, but the 

 ophicephalous and tridentate have long necks, which seem to be wanting in the 

 globiferous. The triphyllous also have long necks, and valves (PI. 95, fig. 22) 

 about .15 mm. long; the blade is the same width as the base, little constricted 

 and very square cut at the tip. 



This species appears to be very well characterized for when compared with 

 tuberculata or crassispina, or with the west coast species of Strongylocentrotus 

 (franciscanus and purpuratus), the differences are so obvious, there can be 

 no question of assigning it to any of those species. The spines of the specimen 

 at hand are all broken, but the primaries were evidently very stout; the remain- 

 ing pieces are bright violet of a light shade. This specimen is supposed to have 



1 orevoiropos = with a narrow way. 



