390 
BULLETIN OE THE UNITED STATES FISH COMMISSION. 
On comparing this species with a more typical Petrosia, such as P. ( Schmidtia ) aulopora Schmidt, 
we find that the regularity of arrangement in the canal system and skeleton of the latter, produced by 
the crossing of radial and tangential canals and spicule bundles, is absent in the Porto Rico species. 
Again, in the latter the spicules are much less closely bound together to form bundles, and the canals 
separating the trabecuke are not so wide. Hence P. Iialich ondrioides is the denser of the two species. 
The loosely arranged spicules of the Porto Rico species suggest a close affinity with Halichondria. 
The spicules of the Porto Rico form are slenderer than in P. aulopora. In a specimen of the latter 
species, in the Museum of Comparative Zoology, the oxea measures 152 by 7 to 8 ft, is smooth, sharp- 
pointed (with exceptions), and somewhat curved or bent at the middle. 
Genus F0LI0LINA 0. Schmidt (1870). 
Sponge a hollow stem with horizontal, lamellate processes embracing the stem. Upper end closed. 
Oscula absent. Texture loose, spongy. Spicules rather stout oxeas, which form polyserial tracts as 
well as a network. Tracts developed especially in the stem, though also radiating out. into the 
processes. 
Foliolina peltata O. Schmidt. 
Foliolina pcltata, 0. Schmidt, 1870, p. 42, pi. iv, fig. 4. 
Station 6067, seven specimens. 
One specimen nearly perfect , 120 mm. long, with stem diameter of 6 mm.; radial length of lateral 
processes, 7 to 10 mm. Processes, of which there are six in this specimen, are at upper end of stem; 
lower end broken across, open. There are six other fragmentary specimens, in three of which the 
stem divides near upper end. 
The lamellate appendages are flattened hollow lobes into which the axial cavity of stem is 
prolonged. Appendage convex above, concave below, and more or less incised round the margin. 
The only pores visible are on lower surface of appendages. 
Skeleton. — Oxea, 320 by 10 //, somewhat curved or bent in the middle, rounding off at each end 
to a sharp point. Wall of the stem, which is firm and 0.5 mm. thick, is supported by a dense renierine 
reticulum strengthened internally by polyserial bundles, which cross so as to produce a coarse network ; 
superficially armed with projecting spicules. Skeleton of lower wall of appendage consists of a reticu- 
lum strengthened internally by radiating bundles of spicules. Upper wall supported by a reticulum, 
without the bundles; outer surface armed with projecting spicules. Cavity of lobe contains a good 
deal of sand. Soft parts of this interesting sponge have been almost completely macerated out. 
Subfamily CHALININH2 (CH ALINE2E ) O. Schmidt. 
Spongin unites, usually envelops, the spicules so as to give rise to a distinctly fibrous skeleton. 
Genus PACHYCHALINA 0. Schmidt (1868). 
Not tubular; skeleton composed of stout fibers, containing numerous spicules, arranged in several 
rows. 
Pachychalina mollis, n. sp. 
Station 6072, ten specimens; station 6075, one specimen; station 6079, two specimens. 
Sponge body branching from the base. Branches, which themselves may divide, subcylindrical, 
long, 8 to 15 mm. diameter. Surface nearly smooth. Consistency compressible and elastic; rigidity 
insufficient (in the wet specimen) for the body to stand erect; body, on drying, becoming stiff and 
capable of standing, retaining its elasticity. Oscula 2 to 3 mm. diameter, arranged on one side of the 
branch in a not strictly uniserial row, commonly 10 to 15 mm. apart. Height of a specimen, from base 
to tip of longest branch, 400 mm. Color, grayish-brown, but with abundant traces of purplish-red, 
probably the natural color. 
Skeleton . — Characteristic spicule is an oxea, about 140 by 7 ft, slightly curved and terminating 
suddenly in points. Oxea occasionally straight; rarely with one end strongylate; still more rarely, 
with one end strongylate and the other tylote. A slender modification (stage in the growth?) of 
the characteristic oxea, present in some abundance; 140 by 2 to 3 ft, with tapering ends. 
