496 Miscellaneous, which has hitherto been neglected by almost all observers, bat which does not in all cases play the part attributed to it by Semper. Here again, the error arises from his having limited his investigations to the Pulmonata. If he had examined certain Gasteropoda in which the ribbon-shaped tongue is as long as the body, as in the Po?natice, or even much longer, as in the Patellce, he would soon have been convinced that the posterior papilla, placed quite at the bottom of the abdominal cavity between the folds of the intestine, never comes in contact with the food. This papilla is in fact the producing organ, the matrix of the rows of teeth which form the radula. In propor-tion as the anterior rows of teeth are worn and thrown off, new ones, destined to replace them, are formed behind. — Siebold and Kollikers Zeitschrifty viii. p. 340-399. Abstract by E. Claparede in Bibl. Univ. de GenevBf January 1857> p. 79. Note on the Invertebrate Fauna of the Baltic Sea. By G. LiNDSTROM. We are accustomed to consider the Baltic as very poor in the lower animals and plants, but this poverty is not so great as has been hitherto supposed. It is certain, however, that most of the species discovered during the last few years belong to the North Sea, and that there is only a very small number belonging to the Baltic itself. But it is precisely the latter, such as Idothea entomon and Ponto-poreia affinis^ which possess a peculiar interest from the resemblance which they present to certain arctic forms {Idothea Sabini and Pontoporeia femorata). Many species which were hitherto supposed to belong to more northern seas are able to live in the comparatively fresh water of the Baltic, and even the mixture of marine and freshwater forms gives a very peculiar character to the fauna of the rocky pools in the vicinity of Stockholm. Amongst the Invertebrata, the Crustacea furnish the greater part of the marine species which are capable of bearing this half-fresh water without losing their purity of type. There are but few Mollusca in this case, and even amongst the animals of this divi-sion there are some which have so modified their original form that they have been taken for species peculiar to the Baltic ; as, for in-stance, Tellina solidula. Not far from Wisby the coast sinks so gently, that at a distance of half a mile from the shore the depth does not exceed 40 fathoms. Close to the shore, where the depth of water is not more than a few feet, the bottom is formed of calcareous pebbles covered with various marine Confervee, with Enteromorpha intestinalis, &c. There, Gam-niarif Planarice, LimncE(je and NeritincB {Neritina fluviatilis) move about. If we advance further into the sea, we find a bank of marly limestone belonging to the formation of Gothland, and covered with Fucus vesiculosus and with Chorda Jilum, At a depth of 8-15 fa-thoms, Ceramia, Polysiphonice and Furcellarice grow. In this zone we find an abundance of Mytilus eduUs, Amphito'e, Paludinellce,
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