246 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Mortensen who has examined the type and other specimens, in regarding it as 

 nearly related to verruculatus. Bell says nothing about the buccal membrane; 

 de Meijere says it is "sehr nacht"; Mortensen that it contains a "great number 

 of small irregular plates." It seems probable that, as Mortensen suggests, this 

 species serves as the connecting link between Lytechinus and the group here 

 called Nudechinus. It is not possible to determine whether the species dyscritus 

 and callipeplus are based on full grown specimens or not but it does not seem 

 probable that they are. 



Test white or whitish more or less shaded with yellowish green abactinally ; spines 

 white or whitish, often yellowish or yellow-green at base; oculars small, 

 all exsert or rarely I insert. 

 Test high; primary tubercles small, little larger than secondaries; primary 



spines short, rather stout; size moderate, up to 30 mm. h. d euerces. 



Test much flattened; primary tubercles very conspicuous; primary spines 



long; size small, less than 10 mm. h. d dyscritus. 



Test and spines not as above. 



Oculars all exsert or sometimes I insert; test variegated with reddish or red; 

 primary tubercles, at least abactinally often reddish; primary spines 

 more or less red or with red bands. 



Spines pale red, not banded callipeplus. 



Many primary spines with 2 or 3 red rings rufus. 



Oculars relatively large, not usually all exsert; test and spines not as above. 



Spines light with 1-4 faint, narrow rings of brown, dull green or pinkish; 



oculars I and V usually insert; size moderate, rarely exceeding 



30 mm. h. d verruculatus. 



Spines not as above. 



Oculars variable, often exsert but often I, or I and V insert; test 

 depressed, low; primary tubercles, at least abactinally, often 

 very dark; spines dull greenish or light; size moderate, seldom 



exceeding 25 mm. h. d anamesus. 



Oculars I and V usually insert, and sometimes IV also; test and 

 spines not as above; gill-cuts in adults usually deep and 

 sharply defined. 



Spines bright yellow-green (K. & V. 282) ; in very young indi- 

 viduals they are darker and are tipped (sometimes banded 

 also) with white; abactinal interambulacral areas very bare, 

 most of the plates above ambitus carrying no tubercles 

 between the two rows of primaries; size moderate, up to 



45 mm. h. d semituberculatus. 



Spines not bright yellow-green; abactinal interambulacral areas 



with secondary tubercles. 



Abactinal interambulacral plates with many secondary 

 and miliary tubercles, only the extreme inner end of 

 each plate, bare; coloration prevailingly rose-purple 

 when young, becoming paler and duller with age, with 

 no indications of either green or deep violet; primary 



