394 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
short upright oscular tubes characteristic of type are present. Par.agastric cavity continuous throughout 
sponge , and about 15 mm. diameter. Tube wall thinner than in type , only 2 to 3 mm. thick. Length of 
longest tube, 150 mm. Color dark amber, with purplish tint. 
Skeleton. — Fibers of the general skeleton slenderer than in type, about 40 p diameter. Dermal 
skeleton, a network of slender fibers, commonly about 8 p thick, with meshes 100 to 120 // diameter. 
From dermal surface small horny villi project, containing a few, sometimes only one, spicule; villi not 
exclusively situated at nodes of network, viz, not all peripheral extensions of radial fibers. Gastral 
surface also provided with a special skeletal network very similar to that of dermal surface; villi longer 
and thicker than on dermal surface, spicules of a villus often forming a pretty compact bundle. The 
origin of the dermal and gastral networks can readily be made out in this variety. In places the most 
superficial meshes of the general skeleton are simply subdivided by finer fibers, which extend between 
and only exceptionally overlie the coarser skeletal fibers. Elsewhere the system of fine fibers has 
reached a further stage of development and forms a continuous reticulum overlying the skeletal fibers. 
Siplionochalina spiculosa Dendy. 
SijriionoehaUna spiculom Dendy, 1890, p.351, pi. i.viii, figs. 2, '2ft: pl.l.xn, fig.3. 
Station 6079, three specimens, fragmentary. 
The habitus of these fragments is interesting when compared with the typical Siplionochalina 
form of body. One specimen is 100 mm. long, of a cylindrical or in places flattened cylindrical shape; 
diameter 10 to 20 mm., except in the middle where body is twice as thick; broken off at both ends. 
On this specimen are five of the large pseudogastral orifices, which in Siplionochalina are typically 
found at the ends of tubular branches. Here all five are lateral, and distributed round the surface; 
two are flush with the surface; two are at the ends of very short, wide elevations; and one is near, 
hut not at, the end of a somewhat more marked elevation. Another specimen consists of a cylindrical 
piece 60 by 20 mm., broken off at both ends, and bearing a somewhat slenderer and longer branch, also 
broken at the end. On this specimen are two of the large apertures, both strictly lateral (not at the 
summit of any elevation whatever). 
Pseudogaster is narrow, somewhat winding in its course, diameter for the most part about 5 mm.; 
in places pseudogaster so narrowed as to be nearly interrupted. The transition in habitus and with 
respect to the pseudogastral system offered by these specimens to the Pachychalina type is obvious. 
Should the pseudogaster become quite discontinuous and the orifices strictly lateral, the sponge would 
have assumed the character of a Pachychalina. In both S. intermedia It. & D. and S. annulata R. & D. 
(Ridley & Dendy, 1887, pi. vii), it may be noticed that some of the orifices are not at the ends of 
tubular branches, but at the summit of small protuberances on the side of a branch or main axis. 
The outer surface in two of the specimens, where intact, is marked with abundant depressed 
membranous areas, more or less circular, perforated in the center, about 1 mm. diameter. Such areas 
frequently connected together so as to form grooves or channels of varying length, often meandering. 
In the third specimen, surfaceshows faintly marked, irregular indentations, but the membranous areas 
are absent. The membranous areas overlie subdermal spaces of corresponding shape. Color of intact 
surface reddish purple. Consistency firm, hard; body incompressible. 
Skeleton. — Spicules. Characteristic oxea, 140 to 160 p by 4 to 6 p. Very slender forms of the same 
spicule, often about 120 by 2 p orsomewhat smaller, are fairly common; transitional forms to character- 
istic spicule present. A modification of characteristic oxea, with one end strongylate, occasionally 
found. Spiculo-fibers stout, containing very numerous spicules, with but little spongin. Primary fibers 
about 60 p diameter, and somewhat slenderer secondary fibers, may be distinguished , mesh work more or 
less rectangular, but rather irregular; meshes wide. On inner surface of tube-wall longitudinal fibers 
distinguishable. Spicules also scattered freely in parenchyma. “The dermal skeleton on the outer 
surface of the tubes consists of a fairly close, polygonally meshed reticulation of stout spieulo-fiber, 
containing a very large proportion of spicules and but little spongin; the average diameter of the fibers 
is about 0.03 mm. The ends of the primary fibers of the main skeleton form projecting nodes in the 
dermal network” (Dendy). 
Genus SPINOSELLA Vosmaer (1887). 
Tubular forms; inner surface of tubes smooth, outer covered with “spines, warts, or prominent 
ridges” (Dendy). 
