ECHINONEUS CYCLOSTOMUS. 57 
The articular loop in valve A is short, straight, and generally has two 
foramina; in valve B, the loop is prolonged either at the right or left side (Pl. 22, 
figs. 4, 14), with a single foramen, while in valve C, the articulation surface slopes 
downward, and the loop is rudimentary. 
The triphyllous pedicellariae were found only in the Jamaican specimens 
(Pl. 23, figs. 16, 17), and mostly in the ambulacra near the actinostome. Even 
in the adult specimens they are very small, 0.04 mm. in height; the bilobed blade 
constitutes the largest part of the valve. 
A comparison of the height of the pedicellariae to the length of the test 
from which they were taken, shows that in young specimens they are propor- 
tionally larger than in the adult. Where a tridentate pedicellaria is 0.13 mm. 
in height on a 4 mm. specimen, it is only 0.51 mm. from a test 34 mm. long. 
The stalk of the pedicellariae differ in form on different parts of the test. 
One stalk (Pl. 26, fig. 31), of an ophicephalous pedicellaria, near the actino- 
stome, from a specimen 18 mm. long from Makemo Islands, with its long rod, 
ending in a head, is similar in form to one of the same order from the actino- 
stome of an adult specimen (PI. 27, fig. 36), from Jamaica. In a specimen 34 
mm., from Lord Howe Island, on the abactinal side towards the apex (PI. 26, 
fig. 19), the stalk is thicker, and without a head, corresponding to one (PI. 27, 
fig. 13), on the abactinal side of a specimen 23 mm. long, from Fakarava Island. 
The stalks of the globiferous pedicellariae have peculiar processes, similar 
to those of some spatangoids, as figured by Mortensen ‘‘Ingolf’’ Exped. Ech., 
pt. 2, pl. 17, 18). Otherwise they show little diversity, though one (PI. 26, 
fig. 17) from near the apical system of a Pacific specimen, 34 mm. long, is more 
solid than some others. The latter are shown on Pl. 27, one (fig. 24) from the 
abactinal surface of a specimen from Barbados, 30 mm. long, and another (fig. 44) 
from a Jamaican specimen only 4 mm, long. 
THE SPICULES OF THE TUBE-FEET. 
Plate 28, figs. 1-14. 
No special difference was found in the tube-feet (Pl. 28, figs. 1-14), though 
a large number of specimens from the Pacific and also the West Indies were 
studied. They all agree in having a disk composed of three plates, but the 
number may vary, as Lovén has shown (Pourtalesia, Pl. 11, fig. 117). In 
some the periphery of the plates is lobed (PI. 28, figs. 5, 6, 13), but usually it 
has an irregular ragged outline, as seen in Pl. 28, figs. 8, 9, 12, 14; figs. 8 and 9 
