There is a hollow upon the back of the animal, where the canal, filled with a reddish juice, passes out, carrying it to a fringed body like a mesentery; and it is there the purple juice is brought to perfection; and afterwards goes to a long sack lying under a kind of horny plate, not like the bone of the cuttle-fish, but like the bone of the _sepia_, or little cuttle-fish, which we call _le couteau_. This bone, or horny substance, is transparent; and is of a triangular figure, or approaching the form of a bivalve shell. On the right side it is fastened by a strong cartilaginous muscle, which binds it to the body of the animal; and on the left it is open and detached, and easy to be pulled up: then it is easy to see underneath both the mesenteric body, and the tube or reservoir of the purple juice. This bone, or horny plate, is covered by a loose membrane, which is by no means attached to it, but capable of being filled and inflated with water or wind. The whole is covered with two membranes, which are continuations of the flesh of the fish’s body: the membranes are loose, and larger than are necessary to the bone: they are wrinkled or rumpled over one another, to cover the whole, and to defend the bone and _viscera_ from all kinds of pressure; but they are ready to stretch one from the other, and leave the parts destined for the purple juice uncovered. They begin a little under the neck, and extend, in the female animal, to the tail, which is flat; and in the male they do not go so low, but end at some distance from the tail. The females are oviparous; for eggs are found in the grand cavity, at the side of the pancreatic body. I have already said, that when the animal is touched, he makes himself round, and throws out his purple juice, as the cuttle-fish does his ink. This juice is of a beautiful deep colour: it tinges linen, and the tincture is difficult to get out. It remains at present to try if we can collect a sufficient quantity of this juice, and to find a means of preserving the tincture; which would then be certainly of great value: to which purpose I may apply myself. When the fish is boiled, or put into spirits, it shrinks up, and loses two thirds of its size; because all the water, which is in the interstices of the fibres, is dissipated, and the dried fibres contract: which clearly appears from dissecting them. Dated at Guadaloupe, 20 Mar. 1757. Peyssonel. LXXVIII. _New Observations upon the Worms that form Sponges. By_ John Andrew Peyssonel, _M. D. F.R.S. Translated from the_ French. [Read Feb. 23, 1758.]