PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 2G9 

 ON CAMABAPH'SrSEBlA, A NEW TYPE ©F SPONttE. 



By JOHN A. RYDER. 



A singular organism, which I will name Camaraphyscma ohscura, was 

 first observed by me on living oysters from Chesapeake Bay, attached 

 to hydroids growing on those molliislis. The single specimen which I 

 obtained measured less than half an inch in length, and consisted of a 

 larger and smaller individual (person), united 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 was capable of being thrown into longitudinal folds and withdrawn or 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 "?). i^o 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 a series of cross- 

 sections, but no evidence of a collar or fiagerium 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 x)owers. No 

 spicules were to be found in any situations ; no fibers, as in the genus 

 Spo7igla; but the whole supi)orting structure consisted, as stated be- 

 fore, of the structureless ectodermal membrane, which was perforata 

 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 ther^ was some sort of communication with the oscular 

 fimnels. Onlv once did I find what I believed to be an iutcrcameral 



