SPONGES COLLECTED IN PORTO RICO. 
405 
extensively developed as widely to separate the dermal membrane from underlying tissue except in 
immediate neighborhood of skeletal pillars supporting the conuli. In the interior, canals 1 to 2 mm. 
diameter are abundant. On the surface are several small funnel-shaped depressions, leading into 
tubular holes occupied by messmates. Color: surface light gray; interior about the same; sandy fiber 
brown ; horny matter itself amber. Living sponge, according to Duchassaing et Michelotti, is blackish. 
On one and the same specimen surface in places is porous to the eye, in places non-porous. In the 
non-porous areas sand grains and bits of spicules are uniformly distributed through the dermal mem- 
brane, there being no reticular arrangement and no visible pores. In the porous regions the sand 
grains and bits of spicules present in the dermal membrane are arranged so as to form a reticulum, 
with more or less rounded meshes having a diameter of about 100 ju, the intervening sand cords them- 
selves having a diameter of about 50 / t . The dermal membrane in each mesh is, as a rule, perforated 
by pores, of which there may only be one, more often several, up to nine; diameter of pores 40 to 80 ft. 
Porous and non-porous regions fade gradually into each other. Moreover, in the non-porous regions 
scattered here and there, in places in some abundance, are small more or less well defined circular 
areas approaching the size of the reticular pore areas. The dermal membrane occupying such areas 
is without pores and without sand grains, the arrangement of the latter round margin of area suggest- 
ing that such areas are spots from which the sand grains are withdrawing to become concentrated in 
bands as in the reticular region. The facts in general suggest that the pores and reticular arrange- 
ment of the sand grains may appear and disappear. 
Skeleton . — In the inner portion of the sponge the skeleton consists of a coarse irregular network, 
main threads of which are irregularly disposed fascicular fibers with diameter 400 to 700 ft. Between 
the fascicles extends a very loose reticulum with meshes from about 500 to 1,200 // diameter, formed 
by fibers frequently about 80 ft thick in the middle, which are usually simple, but which in vicinity of 
the nodes may widen out and become fascicular. Extensive areas, sometimes 3 mm. in diameter, are 
here and there left unoccupied by the skeleton. The distinction between main fascicular fibers and 
the intervening comparatively simple network can not always be made out; in places network can 
only be described as irregular and consisting of fibers which are simple or more or less fascicular. 
From this inner skeleton strong fascicular fibers, 0.5 to 1 mm. diameter, radiate outward and 
upward, terminating in the conuli. Near its peripheral end the fascicular fiber narrows, becoming 
denser, and runs out to a point. The tracts of tissue between the radiating bundles, which are in the 
neighborhood of 10 mm. long and 3 to 4 mm. apart, are unoccupied by fibrous skeleton, except in the 
cases (which do not seem to be common) where a connecting fiber extends between the radiating 
bundles. Such connecting fibers as I have seen vary in diameter from 85 to 170 ju, and are simple except 
at the ends, where they become fascicular. 
Meshes of fascicular fibers (both internal and radiating fibers), and the individual fibers of the 
bundle, vary greatly in size. Meshes, which frequently are elongated in the direction of the fiber, may 
in places appear as mere rounded perforations, frequently 100 to 200 ft in diameter, in a continuous 
mass of horny matter. Elsewhere the structure is much more open, but with large and small meshes 
in close neighborhood, meshes measuring in typical cases 850 by 170 ju, 800 by 300//, 180 by 180 ft. The 
individual fibers frequently have a diameter of about 50 ft, but vary between 20 and 100 ft. 
Sand grains, together with broken pieces of spicules and some foraminifer shells, are present 
and usually abundant in all the fibers of the skeleton, both the individual fibers of the fascicles and 
the separate simple fibers. Similar foreign particles unassociated with horny matter are scattered 
freely through the parenchyma, and are abundant in the dermal membrane and tissue directly 
beneath it, forming a layer from about 40 to 120 ft thick. Throughout the sponge body the charac- 
teristic “ filaments ” are exceedingly abundant, in many places exhibiting an arrangement in bundles. 
Filaments are without spots; diameter in the middle region about 6//; terminal enlargement about 
8 ft wide. 
Hircinia variabilis F. E. Schulze. 
Hircinia variabilis , F. E. Schulze, 1879c, p. 13, Taf. i, figs. 1-5; Taf. in, fig. 1; Taf. iv, figs. 1-15. 
Hircinia variabilis, Lendenfeld, 1889, p.557, pi. 36, figs. 11-14. 
Station 6079, two specimens. 
Shape very variable in the species. One of the Porto Rico specimens, a hemispherical mass 
attached by whole under surface to a Hippo.tpongia inteslinalis, horizontal diameter about 40 mm., 
