140 
of the northern main island, 240 meters 
southwest from the offshore end of the jetty 
of the Government Station. 
It was described by Thiele (1903: 950) 
from the East Indies, where it appears to be 
fairly common. It is redescribed by deLauben- 
fels (1954: 151 ff.) with records from Ebon, 
Ponape, and the Palaus. 
11. Spongosorites porites deLaubenfels 
This sponge was taken by Banner on July 
23 and 26, my numbers 52008 and 52016. 
It was described from the Island of Yap 
(deLaubenfels 1949: 124), and redescribed by 
deLaubenfels (1954: 179). 
12. Spirastrella potamophora deLaubenfels 
This sponge was taken by Banner on Aug- 
ust 15, my number 52002. It was described 
by deLaubenfels (1954: 197). It is extremely 
widespread, although as minute specimens, 
throughout the Marshall Islands, specifically 
at Ebon, Ailing-lap-lap, Majuro, and Likiep. 
It also occurred at Ponape. It is very close to, 
perhaps merely a subspecies of, Spirastrella 
decumbens , which is also widespread in the 
Marshalls and at Truk. This latter was de- 
scribed by Ridley (1884: 470) from the East 
Indies. 
ONOTOA, new genus 
This genus is established for the new species 
Onotoa amphiastra which is designated as type. 
Its family placement is puzzling, because it 
resembles Placospongia , and my opinion is that 
its closest relative is indeed Placospongia. It is 
not here placed in the Placospongiidae, how- 
ever, but is put in the family Spirastrellidae, 
because it conforms to the diagnosis for that 
family. It is a sponge of the order Hadromer- 
ida, having tylostyles as megascleres and 
streptasters as microscleres. The latter include 
distinctive amphispherasters. 
In my monograph of the phylum Porifera, 
(deLaubenfels 1936: 140), the new family 
name Choanitidae was substituted for Spira- 
PACIFIC SCIENCE, Vol. IX, April, 1955 
Fig. 1. Spicules of Onotoa amphiastra X 630 (camera 
lucida drawings), a , Head of one of the tylostyles 
(pointed end not shown); b, streptaster; c, immature 
amphiaster; d , mature amphispheraster. 
strellidae Hentschel, because the genus Choan- 
ites was established in 1822 and Spirastrella 
not until 1868. This action must be reversed 
because Topsent showed (1933: 27) that the 
type of the genus Choanites was not actually 
a sponge, as presumed, but was a compound 
ascidian. 
13. Onotoa amphiastra, new species 
A single specimen was collected by Banner 
on August 1, 1951, my number 52003. It 
occurred at a depth of 60 cm. in a tidepool 
of a Heliopora flat. It is a pale incrusting 
sponge, color in life not given. The consis- 
tency is very tough, and the surface is in 
polygonal areas, both items as in Placospongia , 
but the boundaries of these areas are slightly 
raised, instead of being grooves. The pores 
and oscules are closed, and were doubtless 
minute as is frequently the case for thin in- | 
crusting sponges. 
The ectosome is a dense armour, packed j 
with amphispherasters, whereas that of Placo- 
spongia contains sterrasters. The endosome 
contains fascicular tracts of megascleres, per- 
pendicular to the surface. The megascleres 
are tylostyles, frequently 9 by 630 microns in 
dimensions. A few are somewhat larger, and 
those that are smaller are evidently immature. 
The microscleres include scattered streptas- 
ters, about 30 microns in length with few 
but long rays, and the abundant amphiasters. 
The immature forms of these latter are strep- 
tasters with abundant rays, especially at their 
