ANNOTATED LIST. 97 
25 mm. across and was notable for its conspicuous coloration (plate 6, fig. 2); the bright 
colors were lost on preservation and in its present dry condition it is less than 21 mm. in 
diameter. Two larger specimens were found, nearly 40 mm. across, but they lacked entirely 
any bright coloration, their greenish-gray dorsal surfaces harmonizing well with the under 
side of the rock fragments to which they clung. Either burtonii, like the West Indian A. 
folium, is very diversified in its coloration, or the adults lose the bright colors of youth 
as they mature. 
Asterina exigua.* 
Asterias erigua Lamarck. 1816. Anim. s. Vert., 2, p. 554. 
Asterina exigua Perrier. 1876. Rev. Stell., Arch. Zool. Exp., 5, p. 222 (302).—Koehler. 1910. Indian Mus. 
Ast., p. 129, pl. ix, figs. 6, 7. 
(Plate 7, Figures 6 and 7.) 
This little sea-star is very abundant at Erub, but is much less common at Mer, where 
we met with only a few specimens near the northern corner of the island. At Erub it occurs 
by hundreds in tide-pools on the western side of the island, far above low-water mark. 
The upper surface is variegated with several shades of deep bluish-green with an olive tinge. 
There is great individual diversity in shade, some appearing light from the predominance 
of light shades of green, while others are very dark. The colors are very fugitive in alcohol 
and most preserved specimens are the usual brownish-yellow of museum sea-stars. Diver- 
sity in number of rays is marked but not excessive; of 558 specimens examined at Erub, 
512, or nearly 92 per cent, had 5 rays, 10 had only four, 33, or nearly 6 per cent, had 6, 
while 3 had 7. Conditions at Erub seem to be very congenial to exigua, the individuals 
often reaching the maximum size for the species; the largest measurements I have found 
recorded are Fisher’s (1919)—R =20 mm.; r=14 mm.—but at Erub a number of specimens 
35 mm. across were seen. This is much larger than any of the numerous specimens from 
other localities in the Museum of Comparative Zodlogy collection, few of which are as 
much as 25 mm. in diameter. It was interesting to watch these Asterinas in the pools 
as the tide receded, for they were fairly active (for a sea-star!) and kept moving down the 
surface of the rocks as the water-level lowered. The rate of movement was approximately 
their own diameter per minute. They did not as a rule remain quietly above the water 
exposed to the air. The latter, as well as the current of receding water, apparently serves 
as a stimulus to make them move down a slope. 
At Watson’s Bay, Port Jackson, this little sea-star is nearly as abundant as at Erub, 
but I did not see such large specimens there. It is noticeable that, unlike many Asterinas, 
exigua does not occur ordinarily on the under side of rock fragments, but is found fully 
exposed on the open surface of rocks and ledges, sheltered, however, to some extent in the 
tide-pools, where the full force of the surf does not reach it. 
The distribution of exigua is really remarkable. It is known from the shores of South 
Africa, from St. Paul Island, and from the southern and eastern coasts of Australia; it has 
not yet been recorded from the northwestern part of the Indian Ocean or Ceylon (Sladen 
records it from Mauritius and Madagascar, but I know not on what authority, and Bell 
lists it from the Salomon Atoll) ; it is found in the Andaman and Nicobar Islands, the Philip- 
pines, and Dutch East Indies; Sladen lists it from New Guinea, and there is a good series 
of specimens in the Museum of Comparative Zoélogy from Espiritu Santo, New Hebrides, 
which seems to be the easternmost point where it has been found. It would be fair to inter- 
pret such a distribution as indicating a southern origin, whence the species has spread 
northward along the east African coast and northward clear to the Andamans, along the 
east coast of Australia. Unfortunately, however, it seems probable that Asterina originated 
in the tropics. 
1 Fisher (1919) accepts Verrill’s generic name Patiriella for this species but I am not yet convinced of its 
desirability. 
