PLATE 20. 
1-13. Echinonéus cyclostomus LrEske. 
Valves of tridentate pedicellariae. 
1.— Stalk and head, 0.65 mm. from aboral end of anal system. Specimen measuring 12 mm. long. 
2.— Valve A, 0.30 mm. interior view. 
3.— Valve B, 0.29 mm. exterior view. 
4.— Valve C, 0.26 mm. interior view profile, from aboral end of anal system. 
Test measuring 11 mm. long. 
5.— Valve B, 0.32 mm. exterior view, midway between actinostome and ambitus, in right anterior 
interambulacrum. Test measuring 13 mm. long. 
6.— Valve B, 0.44 mm. exterior view, near actinostome, in right anterior interambulacrum. Test 
measuring 13 mm. long. 
7.— Valve B, 0.40 mm. exterior view, adoral end of anal system. Test measuring 13 mm. long. 
8.— Valve B, 0.33 mm. exterior view, aboral end of anal system. Test measuring 10 mm. long. 
9.— Valve B, 0.38 mm. exterior view, midway between actinostome and ambitus, in odd anterior 
ambulacrum. Test measuring 12 mm. long. 
10.— Valve B, 0.35 mm. exterior view, midway between actinostome and ambitus, in right posterior 
interambulacrum. Test measuring 10 mm. long. 
11.— Valve C, 0.34 mm. exterior view, near actinostome, in left anterior interambulacrum. Test 
measuring 11 mm. long. > 
12.— Valve B, 0.39 mm. exterior view, aboral end of anal system. Test measuring 18 mm. long. 
13.— Valve C, 0.32 mm. exterior view, adoral end of anal system. Test measuring 18 mm. long. 
Figures 1-7, and 9 are from specimens from Fakarava Island, Paumotu Islands, Figures 8, 10-13 
are from specimens from Makemo Island, Paumotu Islands. 
All the specimens were alcoholic. 
Magnification as on Plate 19, 
Of asingle pedicellaria. 
