94 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Ambulacra broaci, about | as wide as interambulacra, or even wider; miliary 

 tubercles rather few actinally, 2-6 on a buccal plate, usually fewer 

 than 10 on larger interambulacral plates, except m the largest speci- 

 mens (25-30 mm. h. d.). 



Primary spines purple or purplish; test tending to become deep purple 



actinally nicobaricum. 



Primary spines green or greenish ; test tending to become purple abac- 



tiually meijerei. 



Ambulacra narrower, about J as wide as interambulacra or less ; miliary 

 tubercles numerous actinally, 8-12 on a buccal plate, usually more 

 than 10 on larger interambulacral plates. 



Primary spines purplish ; anal plates densely covered with rather stout 



miliary spines tonsiim. 



Primary spines greenish ; anal plates each with 5-10 rather slender mil- 

 iary spines Jacobyi. 



Aspidodiadema nicobaricum Dod. 



Aspidodiadema nicobaricum Doderleiu, 1901. Zool. Anz., XXIV., p. 21. 



Plate 50, figs. 1, 2. 



One needs but to compare the descriptions and figures given by 

 de Meijere (1904), Mortensen (1904), and Doderlein (1906), of the pedi- 

 cellarioe of this species, to reahze how elusive and unsatisfactory a classi- 

 fication based to any considerable extent on these minute structures is sure 

 to be. While the " personal equation " will probably explain some of the 

 differences shown by these writers, it seems to be true that this is a very 

 variable species so far as the pedicellarine are concerned. Our Hawaiian 

 specimens exhibit certain peculiarities which would seem to distinguish 

 them from East Indian specimens. Thus, we find the ophicephalous 

 pedicellarifB have only 3 valves, while Mortensen and Doderlein say there 

 are 4 ; however, de Meijere describes and figures them as though there 

 were only 3 in his specimens. Again, none of the Hawaiian specimens have 

 slender, tridentate pedicellarige with curved valves, as figured by Doderlein; 

 however, he says he missed them in most of the " Valdivia" specimens, so 

 this is not an important difference. Again, some of the Hawaiian specimens 

 have very large, stmd tridentate pedicellaria?, with valves (Plate 50, fig. l) 

 over a millimeter and a half in length ; however, these are more frequently 

 absent than not, so no great weight can be attached to them. If we sum 

 up all the observations so far made on the pedicellarioe of this species, the 

 result is as follows : 



