FIG. 1. Tulip Balanus.--(_Lepas tintinnabulum_, Linn.) Shell with six unequal valves articulated by a scaly suture, of which the edges appear to be finely crenellated in the cavity; the form of the valves is conical, aperture ample, and nearly quadrangular. Operculum composed of four triangular pieces crenellated and marked with very projecting transverse striæ, which appear to extend from the top to the bottom; the two posterior pieces are perpendicular, and are applied to the hinder partition of the cavity of the shell; they are terminated by two conical prolongations, of which the points are sharp and diverging. The two foremost pieces are placed in the aperture, in an oblique direction. The colour of this balanus from clear red to violet and brown. [Illustration: Fig. 2.] FIG. 2. View of the upper part of the Tulip Balanus. [Illustration: Fig. 3.] FIG. 3. View of the base. Genus Oyster, (_Ostrea._) [Illustration] Species of oyster, nearly similar to the common oyster, (_Ostrea edulis_,) and of the Huître cuilier, (_Ostrea cochlear_,) their shell rather fragile, almost without lamellæ; upper valve concave, colour rather deep violet, form variable. "Besides these three kinds of Molluscæ, of which the number was considerable, several species of calcareous polypi were found; but those which could be obtained were too imperfect to allow of their being correctly described. "The iron which was used to protect the copper on the bottom of the Constance frigate having been subjected to chemical analysis, the following are the results. "This iron, which was in small fragments, very friable, little attracted by the loadstone, soft to the touch, and soiling the fingers like plumbago, gave out in rubbing it a very strong smell, very much like that of burnt linseed oil. Its colour on the exterior was a brownish yellow, and its interior a blackish grey, studded with little points extremely brilliant. "A short time after they had been taken from the keel of the frigate, where they were covered with a layer of hydrated peroxide of iron, of six or eight lines in thickness, and been enclosed in a paper box, these fragments became strongly heated, and underwent a real combustion by means of the oxygen of the atmosphere; the combustion was accompanied by the production of a certain quantity of aqueous vapour.