548 Notices respecting New Booh. 



a very small scale. The results obtained from them were, 

 however, such as to convince us, that the peculiar condition 

 cannot be excited either in cobalt or in nickel ; at least not 

 in the same way as it is done in iron. This fact seems to in- 

 dicate that the peculiar voltaic state of the latter metal has 

 nothing to do with its magnetic properties. 



Believe me ever to be yours very truly, 

 To Dr. Faraday, fyc. fyc. C. T. Schcenbein. 



LXXIX. Notices respecting New Books, 



A Synopsis of the Family of Naiades. By Isaac Lea, Member of 

 the American Philosophical Society. Large 8vo. with 1 coloured 

 plate. Philadelphia, 1836. 



In most families containing a great number of species the cha- 

 racters are generally found to shade so much into one another, that 

 it is often almost impossible to draw the line of distinction. Such 

 is the case with this interesting family of Mollusca, of which more 

 than 344 species are enumerated. The author divides the family 

 into two genera, Margarita and Jridina. The first he then sub- 

 divides into Unio, Margaritana, Dipsas, Anodonta, and Pleiodon r 

 according to the existence and situation of the teeth. These sub- 

 genera are again divided into Symphynote and Non-Symphynote. 

 Great attention has been paid to the Synonymy, which is enormous, 

 and attended with many difficulties; and even this alone would ren- 

 der the work of great importance to every Conchologist. The nu- 

 merous notes contribute not a little to its value, and evince the great 

 labour and sound judgement of the author. 



Bibliographical Bulletin. 

 Einfluss des Bodens auf die Vertheil d. Gexv. (The influence of the 



soil on the diffusion of Vegetables demonstrated in the vegetation 



of the north-easterlv part of the Tyrol). By Prof. F. Unger, Vienna, 



1836. Svo. 



Our readers will already have seen this work noticed in Meyen's Report 

 on Vegetable Physiology, p. 445, &c, where an extract from it is given : 

 we, however, think it well worth while to direct attention to it, as it 

 contains results which will probably be of vast importance in the physiology 

 and geography of plants. The work is divided into three parts; geological, 

 meteorological, and botanical. The author first considers the chorography, 

 the situation, geological system, springs, nnd lakes in the neighbourhood of 

 Kitzbiihel. Then follows the petrography and geography of a great part of 

 the Tyrol, which on account of the minute details, is of great value to the 

 mineralogist. With the meteorological observations are given two tables on 

 the condition of the barometer and one on the temperature. The botani- 

 cal part is rich in comparisons of the vegetation with the localities, moun- 

 tain and valley, and especially with the geological formations and condi- 

 tions of temperature. Various new observations and experiments have been 

 made on the structure of plants, their nutritive organs, and the substances 

 which they take up. To these are added various maps, plates, and a cata- 

 logue of all the plants, cryptogamiaand phanerogamia, occurring there (1773 



