On the Pharynx of an Unknown Holothurian of the Family Dendrochirotae, in which the Calcareous Skeleton is remarkably developed

ABSTRACT The specimen of which an account is here given was found amongst a quantity of other material dredged in the Sulu Sea, in from ten to twenty fathoms, by Captain W. Chimmo, R.N., of H.M.S. “Nassau,’ 1871, and presented by him to the Anatomical Department of the Oxford Museum. The specimen is unfortunately isolated, and no traces can be found of the body of the Holothurian to which it belonged. Its actual length is about th inches, and because of its large size and the regularity of the arrangement of the calcareous plates with which it is protected, it forms a striking object, which attracts the eye of a naturalist at once. The anterior part of the pharynx itself is complete, with its contained tentacles and calcareous ring, but the retractor muscles are completely torn away, and posteriorly no trace remains of the water vascular ring or its appendages. The membrane which closed the intervals between the rows of radial pharyngealia has also disappeared. The calcareous plates composing the actual ring (annulus) around the anterior region of the pharynx will here be termed annularia; those disposed in rows posteriorly the pharyngealia.