ANNOTATED LIST. 173 
dance of calcareous rods. Pedicels relatively large, not numerous or crowded, confined to 
ventral surface, but not in distinct series there. Dorsal surface well covered with large 
(but much contracted) papilla, not arranged in definite series. Calcareous ring (pl. 37, 
fig. 20) moderately developed, not peculiar; radial pieces higher than interradial, the 
anterior prolongation wide and deeply notched; prolongation of interradial pieces tri- 
angular, pointed. Polian vessel single, very long, and slender. Madreporic canal single, 
small, free, more or less coiled, not whitish but purplish. Genital organs quite 
undeveloped. Anal opening rather large, not guarded by teeth or calcified papille. No 
Cuvier’s organs. 
Caleareous particles in body-wall so abundant that the epidermis is almost brittle, 
of two kinds, buttons and tables; the latter again are of two quite distinct sorts. Ordinary 
tables are abundant, and have the disk (pl. 37, fig. 27) nearly circular, or squarish with 
rounded corners, 0.050 to 0.075 mm. across, perforated by a central and 8 peripheral holes; 
the central hole is only a little larger than the others. Spires (pl. 37, fig. 25) about as 
high as disks are wide, with 2 to 4 cross-beams; the form of the spire shows considerable 
diversity, ranging from slender and smooth with relatively few small thorns at truncated 
tip to stout and rough, with numerous thorns covering the rounded distal half (pl. 37, fig. 
26). The second type of table is much larger and markedly different; only 3 were seen 
and these were from the sides of the body; the disk (pl. 37, fig. 22) is about 0.130 mm. 
across and consists of 4 wide, radiating, flattened rods, lying at right angles to each other, 
the distal tips expanded and perforated by several well-marked holes; the spire (pl. 37, 
fig. 23) is equal to only about one-half the disk diameter and is rather slender and smooth, 
except at tip, where it is finely thorny. Buttons (pl. 37, figs. 28, 29) very numerous, 
0.050 to 0.090 mm. long, the width about 0.60 of the length; most of them are about 
0.075 by 0.045 mm.; there are commonly three pairs of subequal holes and the calcareous 
material between them is about as wide as the narrowest hole; some buttons are bigger 
and have 10 to 12 holes, but they are asymmetrical and obviously abnormal. Pedicels 
with heavy, wide, more or less strongly curved supporting rods (pl. 37, fig. 24), perforated 
at both ends and at the expanded middle; they intergrade with the buttons. Terminal 
plates present. Tentacle rods (pl. 37, fig. 21) very numerous; those in the stalk of the 
tentacle are large, up to 0.400 mm. long, and nearly straight, while those near the tips of 
the branches are very much smaller, 0.050 to 0.060 mm. long, and strongly curved; the 
rods may be smooth or rough, but they are not perforated even at the ends. Color brown; 
tips of pedicels and branches of tentacles deep yellow. 
Holotype: M. C. Z. No. 1009; from under side of a rock-fragment, southeastern 
reef-flat, Mer, Murray Islands, Torres Strait. 
When this little holothurian was collected it was supposed to be a small Actinopyga 
parvula, and hence no particular attention was paid to it at the time. Later examination 
showed that it is a Holothuria and quite different from any of the species (such as difficilis, 
monacaria, leucospilota) which it superficially resembles. The calcareous particles are suf- 
ficiently distinctive to prevent confusion with these or any other species. 
Holothuria arenicola. 
Semper. 1868. Holothurien, p. 81, pl. xx; pl. xxx, figs. 13a, 6. 
This widespread Indo-Pacific holothurian was quite common at Mer, on the south- 
eastern reef-flat. It always occurs buried in the sand, under rock-fragments. The 
tentacles are relatively small and not very extensile; they are completely retracted 
when the animal is first dug out of the sand, and it is not easy then to tell which is the 
oral end. There are no Cuvier’s organs, a rather noticeable fact on the reef-flat, where 
several holothurians of about the same size (150 to 300 mm. long) are conspicuous users 
