142 BULLETIN OF THE BUREAU OF FISHERIES. 
SIGMATOPHORA Sollas. 
Family TETILLIDZ Solias. 
The characteristic megascleres are protrienes, which may be very slender, arranged 
radially. The skeleton in general is usually strongly radiate. 
Tetilla O. Schmidt. 
Typically the ectosome is not a distinct layer, but shades off into the choanosome; 
pores and oscula scattered and not located in special depressions. In some species, 
however, the ectosome is to some extent histologically differentiated and partially 
assumes the character of a fibrous cortex; and in some species there are special depres- 
sions on the floor of which the pores and oscula are located. There is no special cortical 
skeleton. 
Tetilla laminaris, n. sp. (Pl. LVIII, fig. 14; Pl. LIX, fig. 17; Pl. LXVI, fig. 54a to h.) 
Fairly abundant in Newport River in the vicinity of ‘‘Green Rock.’’ The specimens used in pre- 
paring this paper were dredged at half tide, at a depth of 4 feet. 
Sponge body (Pl. LVIII, fig. 14) a vertical lamella, elongated horizontally, the lower part of the 
lamella rooted in muddy sand by abundant fascicles. The lower edge of the lamella is thin; from this 
edge the body thickens gradually to the upper margin, which isrounded. The lamella is sometimes 
folded; the folds vertical. Sponge dense, firm. Color in the fresh state, grayish brown. 
The root fascicles arise from the whole lower edge and the neighboring parts of the lateral surfaces; 
the uppermost, relatively high up on the lateral surface, are short; they increase in length toward the 
lower edge. In the collected specimens the length of the lower rootlets is for the most part 10 to 20 
millimeters, but in one specimen the length reaches 50 millimeters. The rootlets are so abundant 
that the whole lower edge of the collected sponge bears, even after washing, a continuous mass of sand 
held in place by the root spicules. The rootlets were in large part removed from the specimen 
photographed. 
In the type specimen the length is 115 millimeters, the greatest height 60 millimeters, greatest 
thickness 13 millimeters. Smaller and larger specimens are common. The largest specimen in the 
collection is 180 millimeters long, with a greatest height of 70 millimeters and greatest thickness of 30 
millimeters. Relatively shorter and higher specimens occur, but the horizontal length is character- 
istically considerably greater than the height. 
The surface of the upper part of the sponge body looks smooth to the eye. In reality, as may be 
seen with the lens, slender megascleres everywhere project from it for a fraction of a millimeter. 
Numerous small oscula, 0.5 to 1.5 millimeters in diameter, the apertures of short oscular canals, 
are scattered along the upper margin at intervals, 2 to 15 millimeters apart. A few occur in some 
specimens on the lateral surfaces, near the upper margin. Pores about 30 to 60 » in diameter abundantly 
scattered between the projecting brushes of spicules. They perforate the very thin dermal membrane 
and lead into small subdermal cavities which occupy an ectosomal zone about 60 to 80 » thick. The 
intact surface appears dense to the eye; with a lens it is seen to be finely diversified by the minute 
subdermal cavities. . 
The ectosomal zone and the whole peripheral region to a thickness of about 0.5 millimeter is denser 
than the interior, owing to the smaller size of the canals; but, while the canals of the interior are numer- 
ous and larger than those of the ectosome, they are only a fraction of a millimeter in diameter (Pl. LIX, 
fig. 17). No part of the ectosome is differentiated to form a fibrous layer. 
Skeletal framework.—The mesial region of the sponge lamella includes a number of spiculo-fibers 
which pursue, in the main, a vertical direction. From these, radial spiculo-fibers extend outward, 
terminating in a layer of closely set, peripheral, radial brushes, about 800 to 1,000 y in radial length; 
the spicules of the brushes, projecting for the most part a short distance, about 100 »; some of the pro- 
trienes three times as far (Pl. LIX, fig. 17). In the lower half of the sponge the radial spiculo-fibers 
pass obliquely downward. The rootlets are the prolongations of some of the radial fibers and of some 
