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, 



