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PACIFIC SCIENCE, Vol. IX, April, 1955 
tion between ectosome and endosome is 
evident. The megascleres are styles, or some- 
times inequi-ended strongyles up to 20 mi- 
crons in diameter. Their lengths are well over 
a millimeter, the longest always being broken 
during preparation for microscopical study. 
The microscleres include microspined euasters 
(chiasters) often 9 microns in diameter, but 
sometimes as large as 12 microns. There are 
also oxyeuasters 25 to 50 microns in diameter 
that may be immature forms. The distinctive 
spicules are large asters, about 100 microns 
in diameter, with branched tips to their rays. 
This modification also occurs in the spicules 
called sterrasters. These asters are perhaps 
spherasters, but not certainly, because the 
spherical centrum, if present, is obscure. 
Dendy (1916: 266) described a specimen 
from the Indian Ocean as Donatia stellagrandis . 
This was transferred to Tethytimea by deLau- 
benfels (1936: 164). It was subspherical, not 
incrusting, and was stony hard. Its surface 
was a mosaic of polygonal areas, which may 
or may not have originally been tubercles. 
The chiasters were all about 16 microns in 
diameter, and the distinctive spicules 250 mi- 
crons in diameter, hence the species name, 
stellagrandis. 
19- Myriastra debilis Thiele 
This sponge was taken by Cloud on August 
20, my number 52027. This was at the south- 
east end of the reef area known as Rakai Ati, 
at the south side of a large windward point 
of the reef near the center of the Atoll. 
This species was described by Thiele (1900: 
25) from the East Indies. It is not redescribed 
in deLaubenfels, 1954, but it is much like 
Myriastra purpurea which is described therein 
(p. 239). The difference is that the asters of 
debilis are oxyeuasters, not tylasters as in 
purpurea. This latter species is cosmopolitan, 
including occurrence at Ebon. Both species 
have as megascleres large oxeas, and some- 
what more slender anatriaenes and protriaenas. 
They tend to have radiate endosomes, cor- 
Fig. 2. Spicules of Tethytimea stellagrandis X 630 
(camera lucida drawings), a , Head of one of the styles 
(pointed end not shown); b, chiaster; c, oxyeuaster; 
d, one of the abundant distinctive asters. 
ticate ectosomes, subspherical shape and his- 
pid surfaces. 
20. Chondrosia chucalla deLaubenfels 
This species was taken by Banner on Au- 
gust 2, my number 52006, and on August 7, 
my number 52007. It was described by Len- 
denfeld (1888: 74) from Australia. It was 
redescribed and recorded from Ailing-lap-lap 
and Bikini by deLaubenfels (1954: 254). 
REFERENCES 
Carter, H. J. 1879- Contributions to our 
knowledge of the Spongida. Ann. and Mag. 
Nat. Hist . V, 3: 343-360. 
1883. Contributions to our knowledge 
of the Spongida. Ann. and Mag. Nat . Hist. 
V, 12: 308-329. 
deLaubenfels, M. W. 1936. A discussion of 
the sponge fauna of the Dry Tortugas in 
particular, and the West Indies in general, 
with material for a revision of the families 
and orders of the Porifera. Carnegie Inst. 
Wash., Pub. 467: 1-225, pi. 1-22. 
- 1949. New Sponges from the Yap 
Archipelago. Pacific Sci. 3(2): 124-126. 
— 1954. The sponges of the West -Central 
Pacific. 30 6 pp. 12 pis. Oregon State Col- 
lege, Corvallis, Oregon. 
