156 
ing in their morphology to suggest this, how- 
ever, and the very restricted occurrence of the 
sponge does not suggest the presence of an elab- 
orate dispersal mechanism. 
DIMENSIONS: Basal mass, 4.5 cm long; 4.0 cm 
high; 3.0 cm thick. Fistules, 8.5 cm high; 0.65- 
0.75 cm in diameter, 1.1 cm after anastomosis, 
walls 1.2 mm thick; lateral branch, 2.2 cm high; 
0.5 mm in diameter, walls, 0.3 mm thick. Ter- 
minal expansion, 1.5 X 1.0 cm, 0.8 cm high. 
COLOR: In life, bright red; in alcohol, brown 
(Sta. 12) (yY-R 4/2) or dull reddish-brown 
externally, between (RY-R 4/4) and (RY-R 
3/4), to pale brown internally (rY-R 5/4). 
TEXTURE: Firm and brittle with respect to 
the fistules and the dermis of the base; the en- 
dosome of the latter is soft and easily crumbled. 
SURFACE: Smooth, except at the tips of 
branches or on the pore areas where fibres 
FIG. 18 a. Orina saggittaria (Sollas). Sta. 60. 
PACIFIC SCIENCE, Vol. XIX. April 1965 
project and render the surface conulose and ; 
slightly hispid. No oscules are visible, but nu- 
merous skeletal pores are discernible on the 
terminal expansions of the fistules. 
SKELETON: The skeletal pattern of this 
sponge is a curious composite of an irregularly 
isodictyal network with spicule tracts produced 
in the fistules and the terminal caps and of a 
more or less halichondroid skeleton, with spic- 
ules in confusion, lining all large canals in the 
endosome. The dermal skeleton is made up of 
tangentially placed oxeas with no regular ar- |! 
rangement and of abundant sigmas. Below the j 
dermis is an extensive subdermal space system, 
700-800/a deep, across which only isolated oxeas 
extend to support the dermal skeleton. These 
oxeas are part of the irregular reticulation which 
extends throughout the sponge and which is the 
basic endosomal skeleton. Most of the compo- 
nent spicules of the endosomal reticulum, except 
in the subdermal region, are coated with a I 
coarsely granular dark brown material. 6 In addi- 
tion to this skeletal framework, dense aggrega- 
tions of oxeas line all major canals. These spic- 
ules are chiefly disposed at right angles to the 
edges of the canals and give the sponge tissue 
an irregularly tabulate appearance in section. 
In the fistules the skeleton shows little or- 
ganization except toward the production of 
longitudinal tracts. These become extremely pro- 
nounced in the expanded tips of the fistules 
where few extraneous spicules occur. 
SPICULES: Megascleres. Oxeas, slightly curved 
often a little wavy, evenly tapered, 325-375 X 
5.5-10/a. 
Microscleres. Sigmas, with abruptly recurved 
tips and often centrally angulate, 10.5-20.5/a. 
Toxa, of open form, either straight-sided or with 
slightly reflexed tips, 36-50/a. 
discussion: This specimen is the most com- 
plete so far recovered of this species; however, 
the more that is known of its morphology the 
more difficult it becomes to assign conclusively 
to a genus. The form of the sponge is peculiar, 
particularly in the production of fibrous terminal 
expansions to many of the fistules. Most likely 
these are pore sieves, and some tubes may termi- 
6 This appears to be similar to the structure de- 
scribed for Gellius luridus by Lundbeck (1902:64). 
