264 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Test not marked with green and white; primary spines moder- 

 ately or quite long, red or reddish. 

 Test stout, rough, and almost sculptured, with tubercles 



elevated and sutures and pcripodia depressed tylodes. 



Test not very stout nor rough, very closely covered with 



secondary and miliary tubercles horridus. 



Ambulacral plates at and below ambitus often lack primary tubercles; usually 



plates lacking tubercles alternate with those which have them. 

 Valves of globiferous pedicellarise with lateral teeth, at least one on each 



side. 

 Buccal plates do not carry spines; ambulacral plates not twice as many 



as interambulacrals. 



Primary tubercles very small, wanting from many abactinal 

 interambulacral plates; diameter of areolsc at ambitus less than 

 half the height of interambulacral plates; pore-pairs close to 

 central primary tubercle of ambulacral plate, more or less 

 removed from interambulacrum and usually with tubercles 

 between them and marginal suture; primary spines, slender, 



green melo. 



Primary tubercles large, present on abactinal interambulacral 

 plates; areola; at ambitus more than half the height of 

 interambulacral plate; pore-pairs close to or near interam- 

 bulacrum, with no tubercles between them and marginal 

 suture; primary spines more or less stout, not uniformly 

 green. 



Abactinal coronal plates with few secondary tubercles; 

 median abactinal interambulacral areas more or less 

 bare. 



Test not exceedingly flattened, often high, v. d. = .45 

 h. d. or more, usually over .50; one or more peri- 

 proctal plates with at least one spine; test and pri- 

 mary spines usually with more or less red .... acutus. 

 Test very flat, v. d. = .40 h. d. or less; suranal plate more 

 or less circular and very conspicuous but neither it 

 nor any other periproctal plate carries a spine; no red 



(in preserved specimens) anchistus. 



Abactinal coronal plates with numerous secondary tubercles; 



no bare spaces, in the abactinal interambulacra .... Gilchristi. 

 Buccal plates with at least a few spines among the numerous pedicel- 

 larise; secondary spines and tubercles numerous; ambulacral 

 plates nearly or quite twice as many as interambulacrals. 

 Test rather stout, high, v. d. usually more than .60 h. d. ; primary 

 spines short, with secondaries nearly as large; all oculars 

 broadly exsert. 



Color orange reddish or purplish; abactinal spines more or 

 less numerous; coronal plates numerous (in specimens 

 50-60 mm. h. d., 22 or more interambulacral and 50 or 



more ambulacral in each column) esculentus. 



Color white or whitish; abactinal spines few and scattered; 



