SPONGES OF BEAUFORT (N. C.) HARBOR AND VICINITY. 143 
of the lower mesial fibers. The spiculo-fibers are compact, cylindrical tracts in which the spicules 
are arranged longitudinally, without spongin. Between the fibers are scattered megascleres. 
Spicules (P1. LXVI, fig. 54a to h).—{1) Skeletal oxea, smooth, equi-ended, tapering gradually 
toward each end. ‘There are two types which intergrade. The shorter form (fig. 54a) helps to make 
up the spiculo-fibers and is scattered between them. It is also abundant in the root fascicles. It 
is often slightly curved. Common sizes are 600 1 by 10 4 to 1,000 7 by 12 4. A longer form (fig. 545), 
with very slender extremities, generally straight or nearly so, with the ends sometimes curved or bent, 
is abundant in the spiculo-fibers. Common sizes are 1,500 » by 16 pz to 2,300 uw by 20 pn. 
(2) Oxea of the peripheral radial brushes (fig. 54c), inequi-ended, the outer end much the thicker; 
about 800 to 1,000 yw long, 8 thick near outer end, thence tapering gradually to inner end. In each 
brush there are several of these spicules. 
(3) Protriznes of three types. Very slender protrienes, with hairlike cladi (fig. 549); the most 
abundant spicule in the peripheral radial brush; rhabdome near outer end generally about 1 » thick, 
0.5 millimeter long; cladi much thinner, hairlike, 10 to 60 uw long; spicules projecting and covering 
whole surface of sponge, like fine hair. Immediately around an osculum these spicules are slightly 
larger than elsewhere, although the cladi are no thicker. Doubtless some of these spicules develop 
into the stouter forms of protriene, but they can not be regarded as young stages of a characteristic 
skeletal element, for they themselves are a marked feature of the skeleton. 
A stouter protrizne (fig. 54¢) occurs in some abundance in the radial bundles of the lower half of 
the sponge, projecting from the surface; it occurs also, but rarely, in the upper part of body. Monzne 
and diane modifications are present. Rhabdome 6 to 8 w thick near outer end, tapering gradually 
and becoming very slender, about 2 millimeters long. Cladi fairly strong, 30 to 48 uw long, about 4 u 
thick at base. 
Immediately around an osculum abundant protrienes of the type shown in figure 54f occur, the 
spicules projecting in the usual way. Rhabdome at the outer end is about 3 u» thick, thence tapering 
gradually. Cladi about 2 » thick at base, 14 to 40 uw long, commonly of unequal lengths, one cladus 
often considerably longer than the others. With these spicules are mingled the common, very slender 
forms (fig. 549). 
(4) Anatrizenes of the ordinary character (fig. 54d) are abundant in the radial fibers of the lower 
half of the sponge, the entire spicule lying within the body; rhabdome about 6 » thick near cladome, 
tapering gradually and becoming very slender, about 1,500 to 2,000 mu long; cladi about 32 yu long, 
strong, diverging less than 45 degreesfrom rhabdome. The root fascicles are largely made up of similar 
anatrienes, in which the rhabdome reaches a greater length, measuring in some isolated spicules as 
much as 3.5 millimeters. 
(5) Sigmata, giving the common C and S shaped appearances (fig. 54h), are abundant in the ectosome, 
including that of the root fascicles, and in the walls of the canals. They are about 12 w long. The 
surface of the spicule is slightly roughened, sometimes passing into a minutely spinose condition. 
Hyatt has described and Sollas redescribed (Sollas, 1888, p. 46) a Tetilla, T. gravata 
Hyatt, from our Atlantic coast (Buzzards Bay), which is, however, a distinct species 
from the Beaufort form, although Hyatt’s species perhaps extends southward as far as 
the North Carolina coast. At any rate, we have a number of specimens collected at 
Wrightsville, N. C., and Ocean View, Va., by R. Budd Chalmers, of Wilmington, N. C., 
which are certainly not far from 7. gravata, possibly representing a variety. Unfor- 
tunately, all of our specimens are beach specimens, and the surface has been rubbed so 
that the spicular details necessary for a precise comparison can not be made out. 
Discussion of the genus.—Recent writers are not in unison with regard to the use of this 
genus. Lendenfeld (1903) merges into it Chrotella Soll., and later (1906) merges Tetilla 
(+Chrotella) in Tethya (Craniella Soll.). Lendenfeld’s action is based on the occurrence 
of intermediate forms, which make it impossible to divide this group of species clearly 
into the genera recognized in Sollas’s scheme, which are based chiefly on the anatomico- 
histological features of the cortex. The intermediate forms unquestionably exist, but 
