Radials 7 or 8: central 50 mm. long.
salm-dyckianus (43).
Radials 10 or 11: central 25 to 35 mm. long.
maculatus (52).
Radials 13 to 16.
compactus (44).
*** Central spine solitary and hooked.
brunneus (53).
**** Central spines more than one and none of them hooked.
Centrals 2: radials 6 to 20.
scheerii* (40), robustispinus (41), recurvatus (42),
scolymoides* (48).
Centrals 3: radials 6 to 40.
scheerii* (40), scolymoides* (48), echinus* (50),
conoideus (54), neo-mexicanus* (59), arizonicus* (60).
Centrals 4 or 5: radials 6 to 40. scheerii* (40), scolymoides* (48), echinus* (50), conoideus (54), tuberculosus* (56), viviparus* (57), radiosus* (58), neo-mexicanus* (59). arizonicus* (60), macromeris* (64).
Centrals 6 or 7: radials 12 to 40. potsii* (55), tuberculosus*(56), viviparus* (57), neo-mexicanus* (59), arizonicus* (60), chloranthus (62).