392 
BULLETIN OF THE UNITED STATES FISH COMMISSION 
Pachychalina rubens (Pallas) 
Amphimcdon arborescent * , Ducliassaing de Fonbressin et Michelotti, 1864, p. 79, pi. xiv, fig. 2. 
Chalina rubens, Carter, 1S82; p. 276. 
Euchalinopsis rubens, Lendenfeld, 1887, p. 744. 
Playa de Ponce light-house reef, one specimen; station?, one specimen. 
Form variable, .but often “extended into long processes characterized by large round vents. 
Texture firm, resilient. Color dark or light crimson-red” (Carter). Thickly set, rounded, squarish, 
or polygonal subdermal spaces, which are continued directly into canals, give the surface a porous 
appearance. In places, particularly at the upper end of specimens, these spaces have the linear 
arrangement shown by Duchassaing et Michelotti (1. c., pi. xiv, fig. 2), the tissue between the spaces 
corresponding to the “nervures.” Interior excavated by large cavities, about as wide as the 
comparatively solid tissue separating them. Margin of the oscula (“vents”) not usually elevated as 
in Carter’s specimens, but as a rule forming a sharp inwardly projecting edge. 
Skeleton . — The oxeas measure commonly about 160 by 4 )i. In the spiculo-fibers the spicules are 
not arranged very compactly, not filling the fiber. Main fibers (vertical to surface) commonly about 
100 t - 1 thick, with spicules in about eight rows; connectives 60 // and less, with spicules in six or 
fewer rows. Regularity of meshwork, formed by main and connecting fibers, is interfered with by 
numerous spicules, scattered individually or in slender, loose tracts (in both cases surrounded by 
spongin), which irregularly subdivide the mesh. Spongin of spiculo-fiber abundant, though pale. 
Skeletal meshwork close; meshes with rounded corners (glycerin preparation), and about twice width 
of intervening fibers. Meshes of dermal reticulum squarish or polygonal, about 170 // diameter; 
dermal fibers lying over the subdermal spaces slenderer than those over intervening regions. 
Pachychalina areolata, n. sp. 
Station 6088, one specimen. 
Species evidently very close to P. amarcinthus D. et M. A larger number of specimens may show 
transitional forms. 
Sponge body a flattened mass rising up into lobes, some of which are digitate, others compressed. 
Thickness of lobes, and likewise of connecting basal portion, varies from 10 to 20 mm. Conuli absent. 
Surface smooth and coarsely reticular: studded with circular membranous areas, 1.2 mm. in diameter, 
perforated in the center. Oscula 3 to 5 mm. diameter abundant, at or near ends of lobes, on lateral 
surface of digitate lobes, on edges of flattened lobes. Oscula open into large single undivided canals, 
which in many cases extend for some distance into body of sponge, which is nevertheless not tubular 
(siphonoehaline). Consistency firm, but compressible and elastic. Alcoholic specimen colorless. 
Interior extremely porous, as in Pachychalina amaranthus. Directly beneath dermal membrane is 
a single and fairly regular layer of rounded subdermal spaces, about 1.2 mm. in diameter, separated 
by narrow -vertical trabecuke of spiculo-fiber, which support the dermal membrane. Owing to the 
coarseness of dermal reticulum, these trabecuke may be seen in surface view. Pores in meshes of 
dermal reticulum rounded, 50 to 350 ft diameter; absent in some of the meshes. 
Skeleton. — Spicules. Oxea smooth, slightly curved, tapering to sharp points, 200 by 8 jt ; occasion- 
ally rounded at one end. Very slender rhaphid-like oxeas, 160 by 2 //, are found; transitional forms 
between these and the typical spicule common. 
Spongin of spiculo-fiber abundant, containing numerous and not very compactly arranged spicules. 
Fibers in general coarse, of variable diameter, often about 110 /q though varying from 80 to 425 //. 
Except in the peripheral region where there are fibers vertical to surface with some transverse connec- 
tives, fibers form an irregular and coarse network. Abundant free spicules scattered through the 
parenchyma. 
Supporting reticulum of dermal membrane consists of spiculo-fibers, like those of interior, of 
varying thickness, often 60 to 70/(, forming meshes about 600 y in diameter. Meshes sometimes sub- 
divided by one or two slender, often uniserial fibers. Tufts of spicules united by some horny matter 
and usually less than a single spicule in length, project outwards at frequent intervals from dermal 
reticulum. The perforated circular membranous areas, referred to above, are loaded with sand grains 
and spicules, many of the latter being foreign fragments. 
