148 Zoological Society. 



city induced by magnets will ever supply the place of the voltaic bat- 

 tery in effecting chemical decomposition j and he concludes by ob- 

 serving, that " as no increase of electro-magnetic power is gained by 

 increasing the decomposing powers of a battery, and as action and re- 

 action are equal, it appears improbable that we shall ever obtain high 

 decomposing powers by any increase in magneto-electric induction." 



A paper was then read, entitled, " Notice of the Remains of the 

 recent Volcano in the Mediterranean." By John Davy, M.D. F.R.S. 

 Assistant Inspector of Army Hospitals. 



The author communicates an account given by Captain Swinburne, 

 dated the 24th of August, of a dangerous shoal, in latitude 37° 9' N. 

 and longitude 12° 43' E., consisting principally of black nand and 

 stones, with a circular patch of rock, which has been left by the vol- 

 cano that lately appeared in the Mediterranean. Captain Swinburne 

 furnished the author with two specimens of the air which was seen 

 rising from the site of the volcano, in small silver threads of bubbles. 

 These were found, upon examination by chemical tests, to consist of 

 between 9 and 10 parts of oxygenous to 79 or 80 of azotic gases. 



The author adduces arguments in favour of the supposition that this 

 air is disengaged from sea water at the bottom in contact with the 

 loose and probably hot ashes and cinders composing the shoal, rather 

 than that it arises from the extinct volcano. He is also disposed to 

 extend this theory to the explanation of the gases disengaged from 

 hot springs, which are generally found to consist of a mixture of oxy- 

 genous and azotic gases, the former being in less proportion than in 

 atmospheric air, in consequence of its abstraction by oxidating pro- 

 cesses from the air originally contained in these waters. 



ZOOLOGICAL SOCIETY. 



May 14. — Various skins of Birds from Switzerland, presented to 

 the Society by the Administration of the Musee Academique of 

 Geneva, were exhibited. They comprised several species not pre- 

 viously contained in the collection. 



At the request of the Chairman, a paper by Mr. Gould * On a new 

 Genus of the Family Corvida" was read. The genus proposed by 

 Mr. Gould comprehends the Pica vagabunda, Wag!., Pica Sinensis, 

 Gray, and a third species which the author believes to have been 

 hitherto unnoticed. To this group, on account of its arboreal ha- 

 bits, he gives the name of Dendrocitta, applying the specific name 

 of leucogastra to the new species, which he regards as the type of 

 the genus. The shortness and comparative feebleness of the tarsi 

 in Dendrocitta, and its more elongated tail, the feathers of which 

 are equally graduated, except the two middle ones which are much 

 longer than the others, distinguish it from the typical Piece, the com- 

 mon Magpie for example. These characters are in accordance with 

 its habit of wandering from tree to tree in search of its food. It is 

 further distinguished by the form of its bill. All the species yet 

 known are natives of Eastern Asia. 



Mr. Bennett called the attention of the Society to the skin and 



