——— ee 
PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 269 
a 
ON CAMARAPHYSEMA, A NEW TYPE OF SPONGE. 
By JOHIN A. RYDER. 
A singular organism, which I will name Camaraphysema obscura, was 
‘first observed by me on living oysters from Chesapeake Bay, attached 
to hydroids growing on those mollusks. The single specimen which I 
obtained measured less than half an inch in length, and consisted of a 
larger and smaller individual (person), wnited basally to a common at- 
tachment, constituting a corm or colony. The color was yellowish, or 
dirty white; the form of the branches was cylindrical, club-shaped, cov- 
ered by a tough skin (ectoderm?), which was perforated at intervals, 
giving rise to tubular, funnel-shaped, oscular openings of exceedingly 
variable form, according to their condition of expansion. The margin 
of the funnels was entire and exceedingly thin and tough; this portion 
was capable of being thrown into longitudinal folds and withdrawn or 
inverted inwards into the basal portion. These funnels communicated 
at their bases with chambers, lined, apparently, with a single layer of 
cells (endoderm ?). No mesodermal structures were observed, unless 
the single egg which I noticed in the first cleavage stage, from its ap- 
parent position, is to be regarded as a product of this layer. 
The chambers were lined throughout the entire organism with a sim- 
ilar layer of nucleated, columnar cells, as was shown by aseries of cross- 
sections, but no evidence of a collar or flagelium could certainly be de- 
tected as forming the inner extremities of the cells. The embryos 
observed were nearly all in the blastula or morula stage of development, 
and appeared to lie superimposed upon the living cellular pavement of 
the chambers, except the one observed in the stage of first cleavage, 
which seemed to lie in contact with the membranous wall of its chamber. 
The whole organism was composed of very irregular chambers, separated 
from each other by an apparently almost structureless membrane, 
probably of an ectodermal nature. The only evidence of structure here 
was the presence of faint, delicate striations when the edges of the 
walls were transversely cut across and viewed with high powers. No 
spicules were to be found in any situations; no fibers, as in the genus 
Spongia; but the whole supporting structure consisted, as stated be- 
fore, of the structureless ectodermal membrane, which was perforated 
and produced at intervals into the funnel-shaped oscular organs. 
The chambers in the center or axis of the cylindrical body of the or- 
ganism could not certainly be made out to communicate with those next 
to the membranous, funnel-bearing body-wall; but these axial chambers 
appeared to difier in no way from the outer ones in structure. They 
were lined like the external chambers with cells, and, like them, con- 
tained ova in different stages of development, together with brown ma- 
terial, apparently dirt or remains of ingested food, which would appear 
to show that there was some sort of communication with the oscular 
funnels. Only once did I find what I believed to be an intercameral 
