78 Intelligence and Miscellaneous Articles. 



elsewhere, there is intimate connexion between the fossils and their 

 sediment or habitat. Tlie iron-ore frequently accompanj^ing inverte- 

 brate remains had access to them after their death and sepulture. 

 Every serial group of strata marks a distinct centre of life ; a sepa- 

 rate realm or community of animated beings, which may be called 

 epochal, so marked are the differences. The majority of these ex- 

 istences alwaj's perished at the end of the group, because (among 

 other reasons) the new sediment with its new flora was only able to 

 nourish a few, if any, of the old molluscs. All the individual exist- 

 ences were perfect at once from the earliest dawn of life, and all bear 

 evidence of being created on one and the same idea or plan. There 

 is no evidence of multiplication of species by transmutation. The 

 geographic life-centres are also well marked and numerous, forming 

 separate provinces, linked together by a few forms in common, as 

 seen also in other zoological groups, whether of palaeozoic, second- 

 ary, tertiar)-, or recent date. The mollusc having the greatest ver- 

 tical range has the greatest horizontal extension, being found in the 

 most distant regions. The principles among fossils of recurrence, 

 succession, increment, and relative abundance are the same in New 

 York, Wales, and elsewhere ; modified by local circumstances. Re- 

 currence, or reappearance, in difl^erent strata, is, at the same time, the 

 measure of viability in the fossil, and of connexion in the groups. 

 It may partly be due to migration. It is not so common in New York 

 as in Wales ; — in other words, the vertical range of fossils is longer 

 in Wales ; because in the latter area there has been a more universal 

 dissemination of calcareous matter throughout the strata; and because 

 in New York there are three great separate masses of sediment desti- 

 tute of lime, each more than 1000 feet thick ; which were therefore 

 unfavourable for the passage of marine life. A remarkable feature in 

 the uppermost four groups of New York Siluria (the Lower Helder- 

 berg series) is the substitution in them of limestone for the arena- 

 ceous mud of the Ludlow rocks, their contemporaries. It has given 

 tliem a Wenlock character ; but it is to be remembered that the 

 Ludlow and Wenlock Groups of Wales are in close zoological con- 

 nexion ; 74 out of 311 species of organic remains being common to 

 both — or nearly one quarter. Many Silurian brachiopods and some 

 other molluscs occur also in the Devonian ; and some may even be 

 found in the Carboniferous system. 



XI. Intelligence and Miscellaneous Articles. 



NOTE ON THE DECOMPOSITION OF CERTAIN SALTS, PARTICU- 

 LARLY LEAD-SALTS, BY THE ACTION OF THE VOLTAIC CURRENT. 

 BY M. C. DESPRETZ. 



TN an experiment made with the view of determining the propor- 

 -■- tion in which copper and lead are deposited on the negative pole, 

 when a solution of a mixture of acetate of copper and lead is tra- 

 versed by a voltaic current, the author found that the metals, instead 



