Sponges of Palau, I — BERGQUIST 
173 
membrane smooth and skinlike, slightly granu- 
lar to hispid in patches. In two specimens ( Sta. 
92 and 59) the pores have remained open over 
most of the surface and under low magnifica- 
tion give the sponge a regular lacy appearance. 
At irregular intervals the pore reticulation of 
the dermal membrane overlies deep subdermal 
cavities; there is no differentiation of the mem- 
brane at such points, but they presumably rep- 
resent oscular sieves, 0.8-2 .0 mm in diameter. 
SKELETON: The ectosomal skeleton is com- 
posed principally of brushes of subtylostyles 
arising from the endosomal fibres and spread- 
ing tangentially into the dermal membrane. In 
addition to these tangential megascleres, which 
are never abundant, the dermal membrane con- 
tains great numbers of isochelae predominantly 
of the larger category. 
The endosomal skeleton is a system of plu- 
mose fibres cored by subtylostyles invested by 
Fig. 24z. Neofolitispa dianchora (de Laubenfels). 
Sta. 59. 
f 
Fig. 2 4 A Neofolitispa dianchora (de Laubenfels) . 
Isochelae. 
spongin, in the deeper regions of the sponge 
losing most of the spongin and narrowing to 
the point below the surface where they break 
up into subdermal brushes. 
In addition to the ectosomal and endosomal 
fibres, there are abundant interstitial spicules 
which, in the encrusting specimen, predominate 
over the spicules arranged in fibres. This gives 
the skeleton a somewhat confused aspect, but 
the incipient plumose structure is still discerni- 
ble. The specimen from Sta. 92 closely approxi- 
mates the holotype of Folitispa pingens (USNM 
22924) in features of the skeleton. The dermal 
concentration of isochelae is present in the 
type, although not mentioned by de Laubenfels, 
and there are some tangential dermal mega- 
scleres in addition to the subdermal spicule 
brushes. In neither the Palau specimens nor 
the type is there any localization of distinct 
megasclere categories or any occurrence of 
echinating spicules. 
Fibre dimensions are variable, up to 380g in 
diameter in the center of the sponge, narrowing 
to approximately 125g at the point where the 
subdermal spicule brushes arise. 
SPICULES: Megascleres. Straight subtylostyles 
often stair-stepped terminally or occasionally 
modified to tylostrongyles. Some spicules are 
true tylostyles with irregular heads; 262-360 
X 3.5-8.0g ( 342-6.0*0 . 
