SPONGES COLLECTED IN PORTO RICO. 
391 
Arrangement of spicules in body complex and irregular. Spiculo-fibers fairly abundant, 20 to 40 p 
diameter, spicules crowded. Most conspicuous fibers (primary) extend vertically to surface; others 
cut these at a varying angle; others curve, following course of canals. In addition the parenchyma 
contains spicules in part scattered without order, in part arranged in uniserial or slender polyserial 
tracts. Such tracts, together with the scattered spicules and spiculo-fibers, give rise to an irregular 
mesh work; mesh varying greatly in shape, frequently with diameter equal to the spicule length. 
Spongin pale, not forming a distinguishable sheath over larger spiculo-fibers (needs to be demonstrated 
in glycerin). 
In the dermal membrane similar spiculo-fibers, 20 to 80 p diameter, make a close mesh work; 
meshes rounded and commonly 150 to 250 p diameter. 
Species closely akin to P. megalorrhaphis R. & D. (Ridley & Dendy, 1887, p. 23; pi. v); also to 
P. lobata, var. Ridley (Ridley, 1884, p. 404). 
Pachychalina amaranthus (Duchassaing et Michelotti). 
Phorbas amaranthus, Duchassaing de Fonbressin et Michelotti, 1864, p. 92, pi. xxi. 
Pliorbas amaranthus , Carter, 1882, p. 287. 
Station 6079, three specimens. 
Sponge more or less cylindrical, branching from an attached, sometimes creeping, base; branches 
often bent. Diameter, 10 to 20 mm.; length of longest branch, 150 mm. Color, purplish brown. 
Surface covered with numerous slender conuli, 2 to 3 mm. high, projecting outward and upward; 
conuli in lower part of body becoming smaller, less abundant, projecting outward. Dermal membrane 
supported by a skeletal reticulum with meshes sufficiently coarse to be easily seen with the eye when 
the pores are open. Dermal membrane overlies abundant subdermal spaces or canals, and through it 
the sponge tissue separating such spaces may be seen as a coarse reticulum, surface of the sponge thus 
acquiring an areolar appearance. This areolar appearance may be absent in certain parts (is absent 
over nearly whole surface in one specimen); dermal membrane appearing imperforate to the eye, and 
concealing the internal arrangement of cavities and trabecuke. Dermal membrane in such places shows 
under the microscope but few pores; and the appearance of such parts is therefore probably due to 
closure of the pores, and not to greater age, as Carter (1. c. ) believed was the case. 
Scattered abundantly over the surface are depressed, more or less circular, areas, about 2 mm. 
diameter, each consisting of a continuous membrane perforated in the center by a small aperture. On 
or in the membrane are scattered sand grains, foraminifera, broken pieces of foreign spicules, together 
with many spicules, most of which are foreign, arranged radially. The physiological significance of 
such membranous areas, which are present in other ehalinine sponges, demands further study. Oscula, 
for the most part about 3 mm. diameter, are abundant over the upper surface; a few present on that 
part of the surface which looks down. Inner mass of body coarsely porous; in section, total canal 
area visible to eye is greater than the sponge tissue seen. Consistency firm, but body moderately 
compressible and elastic. 
Skeleton. — (1) Characteristic spicule is an oxea, 200 to 220 p by 6 to 7 p, slightly curved or 
somewhat bent in the middle, and gradually pointed. (2) Much slenderer, rhaphid-like oxeas are 
abundant, 160 by 2 p, or somewhat smaller; slightly curved, occasionally in an undulating fashion, 
and with tapering points. Transitional forms between (1) and (2) are found. A modification of the 
characteristic spicule is fairly abundant, in which one end is strongylate. 
In the dermal membrane spiculo-fibers, diameter of which varies greatly, between 20 and 250 p, 
form a coarse reticulum; meshes commonly 200 to 500 p diameter, irregular, but sometimes rectangular. 
From the strands of this reticulum tufts of spicules project outward at short intervals. Such tufts are 
about a spicule in length, and more often consist of a very few, about 3 to 6, spicules; sometimes 
stouter, containing a dozen or more spicules. In the interior similar spiculo-fibers form an irregular 
reticulum, meshes varying in size greatly. Free spicules are scattered in some number through paren- 
chyma, and a few such lie in the dermal membrane. Spongin very pale and scanty, not forming a 
distinct sheath for the spiculo-fiber, although a thin film probably extends over surface of the fiber. 
This film, in a glycerin mount, is obvious in places, particularly in the angles between bundles and 
over projecting separate spicules. 
