JOURNAL OF A VOYAGE TO N. W. AMERICA. 57 narrow & easily shut by the approximation of its mar- gins [?]. The entrance of foreign bodies may be further guarded against by the curvated projecting emminence formed by the body of os hyoides. 2d September. Great abundance of that beautifull zoo- phyte the Medusa Velella of Gmelin is now to be seen floating in every direction. This animal belonging to the genus Velella of Lamarck is distinguished from the Phy- salise of the same author in the direction of the projecting crest which is oblique in the velella & from the presence of a mouth which is absent in the Physalise, The Velella is of an ovate oblong shape, cartilaginous and laminated, the circumferance of a beautifull azure colour umbell, a little convex, with a fine pellucid crest extending ob- liquely from one pole of the animal to the other. The tentacular are not marginal but placed around the orifice of the mouth & of a deep azure colour. The mouth termi- nates, in a deep concave oval cavity of a red granulated appearance. 3d. Last night we had rather foul weather, & accord- ing to the report of those on deck the sea exhibited an uncommonly beautifull phosphorescent appearance. Sev- eral specimens of the zoophyte to whose presence this appearance was probably owing were procured. This animal belongs to the genus Beroe of Mueller. The body is from 1 to 2 inches in length & about the thickness of the finger & round & transparent. On its surface are numerous scattered .tubercles. At the one pole is the mouth which is a circular orifice, but I could detect no trace of tentaculae ; the other pole has a somewhat globu- lar for in, but has no aperture. The cavity .extends through the axis of the body & has an oval form. On the surface of the cavity are many little yellowish papillse which have little black points [orifices?] in the centre ; these papillse
