o4 TROPICAL PACIFIC ECHINI. 
able in a valve B (fig. 12), and a valve C (fig. 13), from a specimen 18 mm. 
long; in the former the blade and base are of about the same size, while in the - 
latter the base is diminished in size and deltoid in shape. 
When selecting valves for illustration from a number of specimens from 
Fakarava Island, ‘‘ Albatross”? Exped. 1899-1900, I decided, after some hesita- 
tion, upon figures to show the greatest extremes in form; thus Pl. 19, fig. 5, 
valve B, with a triangular base, has a remarkably long neck and minute blade 
without serrations, and this has little similarity to a valve A (Pl. 19, fig. 2), 
with serrations and large lateral teeth, or to a valve B (fig. 3), with its large 
ovoid blade, comparatively short neck, and rounded outline of the base, which 
in valve C (fig. 4), is irregular. In connection with these it is interesting to 
note that in a specimen from Barbados, 26 mm. long, I find some of the triden- 
tate valves (PI. 19, fig. 7), showing the character of those from Fakarava Island 
(Pl. 19, figs. 1-4). The only dissimilarity is in the outline of the base, which 
in the specimen from Barbados, is armed close to the neck on both sides with 
large prolonged points. 
Between three specimens 11, 12, and 13 mm. long, and one 19 mm., all from 
Fakarava Island, I should not expect to find great dissimilarity, but valves 
A, B, C, from the same pedicellaria in the smallest specimen, have broad rounded 
blades with large lateral teeth and stout symmetrical bases, which including 
the articular loop, are as long as the blade. Their form has no similarity to a 
valve B (PI. 20, fig. 5), from midway between the actinostome and the ambitus 
in the right anterior interambulacrum, or to another valve B (PI. 20, fig. 6), 
from near the actinostome in the right anterior interambulacrum, which has a 
long deltoid base, and short triangular blade; neither is it like another valve B, 
(Pl. 20, fig. 7), from the adoral end of the anal system. Even fig. 9, a valve B, 
with its well-marked lateral teeth differs from the others. 
The material from Port Antonio shows still further diversity as seen in a 
comparison of nine valves of the series B, one of them (PI. 23, fig. 12) from the 
odd posterior interambulacrum, actinal side, near the ambitus, with its broad 
neck which gradually unites to the blade, contrasts with one (fig. 73) from the 
aboral end of the anal system, in which the blade is nearly circular. Both 
valves are of equal height, and from the same individual, measuring 25 mm. 
in length. I find another case of a valve (fig. 14) from the adoral end of the 
anal system of a specimen 26 mm. long, where the remarkably large base is 
almost square, the blade broad and short, and ending in a sharp point; this is 
quite unlike a valve (fig. 15), from the left posterior interambulacrum near the 
