SPONGES OF BEAUFORT (N. C.) HARBOR AND VICINITY. 153 
Beneath the dermal layer of the fistula and about a spicule’s length from it lies the fibrous layer. 
The two are connected by smali bundles of spicules or by single spicules, which extend radially or 
obliquely to the surface between the subdermal spaces (fig. 30). 
The fibrous layer consists of polyspicular spiculo-fibers (figs. 30 and 32), which pursue a longitu- 
dinal course, dividing and anastomosing to some extent, interconnected by slender tracts of spicules 
or by scattered spicules forming a secondary reticulum. The secondary reticulum varies in character 
in the same fistula. The mesh may be polygonal, with a side equal to the length of a spicule, unispicular 
in one region, polyspicular in another; or the spicules may be thickly and confusedly crossed, giving 
the mesh a side less than the length of a spicule; or the mesh may still be polygonal, but its sides two 
or three times the length of a spicule and formed by polyspicular tracts. At the nodal points of the 
reticulum there isspongin. The main longitudinal fibers are 30 to 80 u thick; spicules of a fiber arranged 
lengthwise, closely packed, and bound together by a very small amount of spongin, which does not 
form a covering for the fiber. 
Internal to the fibrous layer the fistular wall contains almost no skeleton. At most a few spicules 
project radially and obliquely inward from the fibrous layer, and here and there a free spicule is found. 
Skeletal framework of basal part of sponge.—Where the surface of this part of the sponge has been 
preserved, an ectosomal skeleton is found much like, nevertheless somewhat different from, that of the 
fistula. There is a dermal layer, two or three spicules thick, of tangential megascleres, which cross in 
every direction. These are united, as in the fistular wall, by spongin at the nodal points, but the spicules 
are so abundant that they can not be said to form a reticulum. Still they are not as densely packed 
as in some species; everywhere minute angular spaces, commonly about 12min diameter, are left be- 
tween them. 
Beneath the dermal layer and visible through it spiculo-fibers, like those of the fistula, form a coarse 
and very irregular reticulum. 
The choanosomal skeleton consists chiefly of abundant scattered single spicules, crossing one another 
in all directions, without spongin. Here and there the spicules are combined to form loose tracts. 
The Beaufort species is nearest P. reticulatum Tops. from the Azores (1904, p. 238). 
But in the latter the spicules of the dermal layer are loosely intercrossed; the fibrous 
layer of the ectosome is a network with subequal, round, or oval meshes; and the oxeas 
are larger, 175 to 210 uw by 3 to 13 yn. 
Lundbeck (1902, p. 56) dissolves Carter’s group Phloeodictyine and distributes 
the genera (Rhizochalina, Phlceodictyon, and Oceanapia) among the Chalinine, Renier- 
ine, and Geiliine. The treatment is logical if we regard only the spicules (and, in the 
case of Rhizochalina, the character of the spiculo-fiber). Topsent (1904) and others 
have followed Lundbeck. Dendy (1905), keeping in mind the presence of fistule and 
the dense ectosomal skeleton, constituting a rind, retains the group, adding to it 
Histoderma, Sideroderma, and Amphiastrella, which necessitates placing it in the 
Desmacidonide. The group, as Dendy remarks, seems to be a natural one. 
Subfamily PHORIOSPONGINZ: Lendenfeld, 1888, 1889, ernend. 
The skeletal fibers are very areniferous, sometimes partly spicular; they may be 
reduced to rows of sand grains united or not by spongin. Skeleton usually reticulate, 
but sometimes consisting of independent fibers or of scattered sand grains. The mega- 
scleres are monaxonid, monactinal or diactinal, or both. ‘The microscleres are chelze 
and sigmata, but either or both may be lacking. The flagellated chambers are (always?) 
eurypylous and large. 
