Sponges of Palau, I— Bergquist 
149 
Fig. 13. Cribrochalina olemda de Laubenfels. Sta. 
135. 
by de Laubenfels and Is visible only in speci- 
mens preserved in alcohol ) 
DISTRIBUTION: Palau Islands (de Laubenfels). 
genus Xestospongia de Laubenfels 
Xestospongia de Laubenfels, 1932, p. 115. 
Neopetrosia de Laubenfels, 1949, p. 10. 
Neopetrosia de Laubenfels, 1954, p. 81 pars. 
Xestospongia exigua (Kirkpatrick) 
Fig. 14/, ii, Hi 
Petrosia exigua Kirkpatrick, 1900, p. 139, pi. 
XII, fig. 7; pi. XIII, fig. 4. 
Xestospongia exigua de Laubenfels, 1949, p. 
126 . 
non Xestospongia sapra de Laubenfels, 1954, 
P- 79, fig. 48. 
Neopetrosia pandora (pars.) de Laubenfels, 
1954, p. 81, fig. 49. 
OCCURRENCE: Sta. 10,47, 100. 
DESCRIPTION: One specimen (Sta. 47) of 
this species is an erect sponge with numerous 
slender branches which sometimes anastomose; 
the other two are repent, with extremely irregu- 
lar stout branches (Table 2 ) . 
SURFACE: Characterized by a reticulate pat- 
tern formed by the ascending endosomal col- 
umns which fan out distally and support the 
aspiculous dermal membrane. This pattern is 
uniformly evident in two specimens (Sta. 47 
and 10) where the endosomal spicule tracts are 
narrower and the texture of the sponge is cor- 
respondingly softer; it is less pronounced but 
still visible in the third specimen. All of de 
Laubenfels’ specimens of Neopetrosia pandora 
show this reticulation; it is also plain in his 
specimen of Xestospongia exigua from Yap, 
and was described by Kirkpatrick ( 1900) for 
the type specimen of Xestospongia exigua. The 
illustrations of Petrosia similis Ridley and 
Dendy (PL III, figs. 3, 4, 6) , although lacking 
in detail, convey the impression of a reticulate 
surface as is described in the text. 
SKELETON : In all three specimens the skele- 
ton is basically an isodictyal reticulation with 
unispicular to multispicular ascending tracts 
developed to varying degrees. In the specimen 
from Sta. 100 these tracts are abundant and up 
to 300/x wide. In other specimens tracts, 36- 
50/x, six to eight spicules wide, are common; 
larger tracts up to 100 /x wide occur infrequently. 
In all cases numerous spicules occur usually 
aligned parallel to the ascending tracts. 
Faint traces of spongin occur distributed 
sporadically along some of the ascending tracts. 
Immediately below the surface the ascending 
tracts fan out into brushes, 62— 187/x across, the 
outer spicules of which project slightly beyond 
the dermal membrane. 
