Part 16

Radials 3: centrals 3. alternatus (1)

Radials 7 or 8: tubercles 40 to 50 mm. long. longimamma (36).

Radials 10 to 12: tubercles 12 to 15 mm. long. gummiferus (8).

++++ Radials numerous (16 to 60), capillary or bristle-like.

Radials 15 to 30, slender but rigid (bristly). acanthophlegmus(2), densispinus (4), bispinus (14), rhodanthus (26), sulphureospinus (27), palmeri (29), pringlei (32).

Radials 30 to 60 or more, mostly capillary. tetrancistrus* (22), capillaris (28), texanus* (31), spaerotrichus (33).

***** Central spines more than one and but one of them hooked.

Radials 10 to 15. goodrichii* (16), setispinus (24).

Radials 15 to 30. pondii (17), grahami* (19), bocasanus (20).

Radials 30 to 60. tetrancistrus (22).

****** Central spines more than one, and more then one of them hooked.

Radials 8 to 12. wrightii* (15).

Radials 30 to 60. tetrancistrus (22).

II. Tubercles with a more or less prominent groove.

* Central spines none.

+ Radials whitish and rigid, oppressed (pectinate) and interwoven with adjacent clusters.

Depressed-globose and simple. compactus (44).

Globose and simple. radians* (45), corniferus (47).

Cespitose. pectenoides (46), sulcatus* (49).

++ Radials more slender and spreading.

Radials 10 to 17. missouriensis* (37), similis* (38), macromeris* (64).

Radials 30 to 50, capillary. dasyacanthus* (51).

** Central spine solitary, not hooked.

+ Central spine porrect.

Radials 6 to 17. missouriensis* (37), robustior* (39), scheerii* (40).

Radials 30 to 50, white and capillary. dasyacanthus* (51).

++ Central spine curved downwards.

Radials 8 to 12. sulcatus* (49).