150 
PACIFIC SCIENCE, Vol. XIX, April 1965 
TABLE 2 
CHARACTERISTIC 
STA. 10 
STA. 47 
STA. 100 
Color in life 
blue 
Color in alcohol 
greyish-brown externally 
(rY 4/2) , reddish-brown 
internally (YR 4/ 6) 
brown (yY-R 4/2) 
pale brown 
(Y-R-Y 6/4) 
Branch height 
repent 
mostly broken but greater 
than 20 cm 
Branch diameter 
almost massive in form 
owing to frequent 
anastomoses 
0.9-2. 5 cm 
0.4— 1.2 cm always 
cylindrical or oval 
extremely irregular 
often flattened 
Q.6-3.0 cm 
Texture 
firm, just compressible 
firm, just compressible 
cork-like, extremely brittle 
Oscule diameter 
1.2-2. 5 mm 
1.0-2. 5 mm 
0. 8-4.0 mm 
Spicule dimensions 
105-132 X 3. 0-5. 5m 
99-126 X L5-5.0M 
105-130 X 3. 5-5. 5m 
DISCUSSION: The initial diagnosis of Xesto- 
spongia de Laubenfels (1932) reads, "charac- 
terized by having only oxeas as spicules and 
these so abundant that any reticulate arrange- 
ment is obscured; there is no special dermal 
skeleton.” On the same page, in the description 
of the type species, Xestospongia diprosopia , 
an endosomal reticulation prominent enough to 
enable measurements of the meshes is described. 
A second species, Xestospongia vanilla , de- 
scribed in the same work conforms more closely 
to the generic diagnosis. 
It is difficult to see the differences between 
Xestospongia de Laubenfels and Neopetrosia 
de Laubenfels if only the generic diagnoses are 
considered. Neopetrosia , with type species Hali- 
clona longleyi, is defined as "differing from 
Haliclona by having a smoother surface, more 
brittle consistency and other important differ- 
ences which we are not yet ready to discuss.” 5 
The erection of Neopetrosia was premature and 
it remains an incompletely defined genus. 
It is unquestionably correct that there are at 
least two separate groups of sponges in Petrosia, 
some with the spiculation of the type species 
( Petrosia dura ( Schmidt ) ) possessing a der- 
5 This refers to Bergmann’s work on the sterols of 
sponges. Those of H. longleyi were distinctive; un- 
fortunately no further data have been produced which 
pertain to this species or to the genus Neopetrosia. 
mal skeleton and having a rock-like texture, 
others with oxeas, no dermal skeleton, retaining 
the stony texture and having little or no trace 
of a reticulate skeleton. The erection of Xesto- 
spongia for the latter group was thus justified, 
but the genus requires redefinition in terms of 
western Pacific material which has been sub- 
sequently assigned to it. 
The specimen from Yap (usnm 22733), de- 
scribed as Xestospongia exigua (Kirkpatrick) 
by de Laubenfels ( 1949), is identical except in 
form with the holotype of Neopetrosia pandora 
de Laubenfels 1954 (usnm 23046) and is dis- 
tinctively different in spiculation from Xesto- 
spongia sapra de Laubenfels. Xestospongia sapra 
has oxeas, strongyles, and styles of irregular, 
curved, even wavy form and has a microconu- 
lose surface. De Laubenfels (1954) stated that 
his specimens of X. exigua and X. sapra both 
belonged to sapra; this is not the case. 
In describing Neopetrosia pandora , de Lau- I 
benfels mentioned the great variability of his 
specimens in details of spiculation and in habit. 
This can be endorsed from a study of the type 
series and the Palau collections. In view of this 
variability it is difficult to see why de Lauben- \ 
fels did not relate his Yap specimen of X. 
exigua to this complex. It is possible that de 
Laubenfels described more than one species 
under N. pandora; specimen 403 (usnm 23024) 
