SPONGES OF BEAUFORT (N. C.) HARBOR AND VICINITY. 141 
free portions of the lobes. The upper margins of the lobes are fairly sharp and have in the alcoholic 
specimen a dense, whitish appearance. These margins are commonly notched and undulating, but 
the portions between the notches may be produced into ascending lobules. The central lobes are the 
longest; their radial length is about one-half the vertical diameter of the whole sponge. Probably the 
basal part of the sponge mass has been built up during growth through the gradual incorporation of lobes. 
The surface when examined with a lens is seen to be minutely roughened and well covered with 
projecting spicules. The ectosome includes very numerous subdermal cavities, varying considerably 
in diameter from about 150 to 1 millimeter (Pl. LVII, figs. 10,11). The thin, dermal membrane roofing 
these over is perforated by pores 20 to 4o » in diameter, several opening into each cavity. Most of the 
pores are closed, but enough are open to show the arrangement. -Smali oscula about 1 millimeter in 
diameter occur on the upper margin of the lobes. Probably they are naturally numerous, but now 
for the most part closed. 
The interior of the sponge is dense as compared with the ectosome, but sections (Pl. LVII, fig. 10) 
show that it, too, is greatly excavated by canals, most of which are small, about 100 to 300 uw in diameter, 
with some largerones. Flagellated chambers, ellipsoidal and 20 to 25 «1 by 30 to 35 u, are abundant in the 
choanosome. The thin trabecule and sheets of sponge tissue are favorable for histological study. ~ 
Spicules.—Tylostyles smooth and slightly curved, with well-developed, rounded head (Pl. LXVI, 
fig. 52). The shaft is very slightly thicker in the middle than near the head end, tapering at the other 
end to a sharp point. The head is not infrequently irregular, sometimes constricted near its middle. 
Range in size for whole sponge, 200 by 6 » to 460 by rou. 
In the interior the larger sizes are abundant, perhaps predominate. The spicules of the dermal 
skeleton are, in the average, smaller; the common range being 200 by 6 u to 320 by 8 n. 
Skeletal framework.—The skeleton (Pl. LVII, figs. 9, 10, 11) is made up chiefly of abundant and 
fairly compact tracts of megascleres, which pursue a rather vaguely radial course in the basal part of 
the sponge, becoming distinctly longitudinal inthe lobes. In aslice of some size through the basal part 
it is easy to see that, while many individual tracts curve in all directions, the skeleton as a whole ex- 
hibits a radial arrangement. The spicules lie more or less longitudinally in the tracts and are abun- 
dantly scattered between the latter. Spongin is absent. 
From the internal skeleton short tracts are given off which extend outward, usually upward and 
outward, through the ectosome and terminate in dermal brushes of divergent spicules (fig. 11). The 
dermal skeleton includes, in addition to the brushes, a good many single, radial, and projecting megas- 
cleres and abundant tangential megascleres scattered without order. The spicules of the dermal brushes 
usually project a considerable distance, often about half the length of the spicule. The spots at which 
they project are, as a rule, either not elevated, or only slightly elevated, over the surface in general; 
but in places these spots are elevated high enough to be called ‘“‘conuli.’’ The difference may in part 
be due to contraction, 
In the upper margins of the lobes, or of the subdivisions of the same, the dermal brushes are so 
closely set as to form a continuous furze, in which the longitudinal skeletal tracts terminate. It is 
this dense aggregation of dermal spicules that gives to these margins their whitish appearance in the 
alcoholic specimen. 
The lobes of the Beaufort sponge are, of course, structures quite different from the 
papille of the Polymastide. 
In its extensive development of the ectosomal canal system S. wndulatus resembles 
the species grouped under Topsent’s genus Pseudosuberites: P. sudphureus (Bean), P. 
hyalinus (R. and D.), P. andrewsii Kirkp., P. exalbicans Tops. But this particular 
feature does not, it seems to us, constitute sufficient ground for excluding the sponge 
from the older genus. Probably when the canal system of the numerous Suberites 
species has been studied more extensively, considerable variation will be found in this 
matter within the genus. 
110307°—21——10 
