Sponges of Palau, I— BERGQUIST 
143 
The fibres are from 25 - 80 g in diameter. 
Fragments of sand and spicule debris occur in 
the dermal membrane on one surface only but 
form a very thin layer, not a continuous cortex. 
HISTOLOGY: A dermal membrane 12-20/a 
thick overlies a cortical region of variable thick- 
ness. The dermal region is made up of a densely 
cellular layer with little extracellular matrix; 
the cells have prominent nuclei and granular 
cytoplasm. Deep to this layer is a zone in which 
the concentration of spongin A greatly exceeds 
that of the cortex; this layer appears to serve 
as a basement membrane. The cortex contains 
many granular spindle-shaped cells with prom- 
inent nuclei set in a clear ground substance. 
The endosome is cavernous and contains 
large numbers of symbiotic blue-green algae. 
Flagellate chambers are abundant, large, and 
eufypylous. 
Dimensions of flagellate chambers. 
Holotype, usnm 22971: 59-70 X 36-62/* 
Sta. 47 : 62-75 X 37-48/* 
Sta. 219: 55-75 X 38-48/* 
DISCUSSION: The species of Dysidea are ex- 
tremely difficult to define on morphological 
grounds since, frequently, specimens of funda- 
mentally different habit are identical or closely 
comparable in internal structure. De Laubenfels 
Fig. 8 a. Dysidea chlorea de Laubenfels. Sta. 219- 
USNM 23705. 
considered it possible that Dysidea chlorea was 
merely a variant of D. fragilis. 
Much attention has been given to the varia- 
bility of D. fragilis (Burton, 1934; de Lauben- 
fels, 1948), which appears to be a sponge in 
which the amount and type of debris incor- 
porated in the skeleton can vary within wide 
limits; detritus is, however, not usually present 
in the form of a superficial cortex. The presence 
of such a sand cortex is characteristic of D. 
chlorea . A further difference between the two 
species is the nature of the fibres, which are 
extremely fine and regular in all specimens of 
D. chlorea. These features, in conjunction with 
the peculiar growth form, are sufficient to sep- 
arate D. chlorea and D. fragilis. 
In D. herbacea a complex lamello-digitate 
habit is coupled with coarse, irregular fibres 
and a well-defined sandy cortex. Until it is 
known to what degree these features are rele- 
vant in separating the species of Dysidea , it is 
practicable to retain both D. chlorea and D. 
herbacea. 
DISTRIBUTION: Marshall Islands; Hawaii (de 
Laubenfels ) . 
Fig. 8b. Dysidea chlorea de Laubenfels. Cross sec- 
tion of the sponge base showing the loose fibre net- 
work. 
