24 HAWAIIAN AND OTHER PACIFIC ECHINI. 



length; anterior petals more than .80 as long as unpaired one; 

 lower surface not usually markedly concave, though mouth is 



distinctly sunken japoniciis. 



Size small, not exceeding 7.5 mm. in length; width usually not .80 



length; anterior petals short, scarcely .7.5 as long as unpaired 



one; lower surface strongly concave. 



I'npaired petal widely open, with numerous pore-pairs (36 on 



each side in petal 10 mm. long); petaloid area not at all 



depressed li)l,>i>etalus. 



rnjiaired petal nearly closed, with fewer pore-pairs (28 on each 

 side in petal 14 mm. long); petaloid area in adult more or less 

 depressed, at least the distal portion lying lower than the thick- 

 ened test-margin though the apical system may be much higher reliculatus. 

 Test rather low (v. d. = .1.5-. 22 test-length), with thin margins (.04-.0S 

 test-length); aboral surface more or less fiat distal to petals; lower sur- 

 face flat or shghtly and gradually concave. 

 Primary tubercles numerous, small; on each ridge between purc-pair.s 

 of unpaired petal, there is a single regular series of 6-15; unpaired 

 petal with poriferous areas converging distally though petal may 

 remain oi)en. 

 rn|):iired petal with relatively few pore-pairs (about 50 on each side 

 in a petal 40 mm. long); median area of petals markedly 

 obovate, nan-ow proximally and broadest distally; poriferous 

 areas converging rather abruptly, and tending to close the pet- 

 als, especially the anterior and posterior pairs humilis. 



Unpaired petal wdth more numerous pore-pairs (60-70 on a side in a 

 petal 40 mm. long); median. area of petals not obovate, usu- 

 ally as wide at the middle as anywhere; petals more or less 

 open. 

 Test about .90 as wide as long or wider; anterior lateral petals 

 about .90 as long as unpaired petal. 

 Unpaired petal broad and widely open; its breadth is de- 

 cidedly more than half its length and it is at least twice as 



widely open as posterior pair proalralus. 



Unpaired petal narrower wdth poriferous areas more con- 

 vergent; its breadth seldom exceeds half its length and is 

 usually less; it is sometimes widely open but not more so 



than posterior pair- roiimdus. 



Test about .80 as wide as long; anterior lateral petals short, only 



about .80 as long as unpaired one subdepressus. 



Primary tubercles scattered, rather large especially on interambulacral 



areas orally; on each ridge between pore-pairs of unpaired petal, 



there are not more than four and often there is only one or none; 



unpaired petal short, only .25-.30 test-length, with poriferous areas 



parallel or somewhat diverging (in small specimens somewhat 



convergent). 



Primary tubercles and their spines orally not strikingly peculiar; 



petals (at least in adults) much wider than half their length. 



Test .90-.95 as wide as long, not depressed at distal end of 



petals; color, yellowish brown becoming deep green after 



