Of Crustacea we saw twenty different kinds; among them a _Gonoplax_ of the middling size, and as white as the coral-sand, among which it lives, on the shore. The _Hippopus_ found here differs from the _maculatus_ already known by the much greater elevation of its shell. The large _Tridachna_ is the _Tr. squamosa Lam._ It is very unusual to meet with an animal belonging to the family of Lepades in tubular holes made in the coral rocks, as is the case with the _Lithonaetta N._ Among the twenty kinds of tabular coral here observed, there was not one of those collected at O Tahaiti; there were three new _Distichoporae_, _Seriatipora_, six kinds of _Madrepora_, two _Porites_, four _Astrea_, _Pocillopora caerulea_, and another kind, forming broad, yellow, leafy masses, the slime of which stings like a nettle; _Cariophyllaea glabrescens Cham._, and _Tubipora_, with red animalculae. A calm of several days, between eighteen and twenty degrees of north latitude, during our passage to Kamtschatka, afforded opportunities for the observation of several remarkable animals. A small animal of Lamarck's family of Heteropodes, with two rows of separate fins, received the name _Tomopteris_. Secondly, a _Salpa_, of the class which lives apart and has fine long fibres projecting from the hinder part of the body. Thirdly, a small animal, nearly allied to the _Diphyes_, the soft part of the body, which contains the tube for receiving nourishment, having no air-bladder. Fourthly, a small _Beroe_, having the power of drawing in its fins. Fifthly, a very small _Porpita_. The sixth animal was a very remarkable crab, the triangular shell on the back, only two lines in length, provided with a spike from eight to ten lines long, (_Lonchophorus anceps_,) projecting both before and behind. Professor Germar has given to a species of beetle the name _Lonchophorus_, but the same had already been described by Mac Leay, under the name of _Phanaeus_. Seventhly, an animal belonging to the class _Arthrodiae_, (_Arthronema N._) the exterior consisting of stiff tubes, in the interior of which is afterwards found a skin, which eventually divides into separate parts. Eighthly, a _Clio_, about a line in length, with a projection from the globular part of the body. Ninthly, a second variety of _Appendicularia_, described by my friend and companion, on board the Rurik, A. von Chamisso, in the tenth volume of the _N. Acta Acad. Leop. Car._, which proved to be a species of Mollusca belonging to the Heteropodes of Lamarck. Tenthly, a _Pelagia_, scarcely, if at all, to be distinguished from the _Panopyra Per._ Lastly, a new kind of _Cestum_, _C. Najadis N._