4 



On the Determination of Verdet's Constant. 



[Nov. 15, 



nified, are appended to the text. The author remarks that the first 

 indication of since restored species, e.g., of the Diprotodon, as a large 

 extinct Marsupial, was a portion of a tooth, and corresponding- 

 accessions of fossil remains may be expected to lead to a like recon- 

 struction of the present animal. He is indebted to E. P. Ramsay, 

 Esq., F.L.S., for casts of the first found specimens of the teeth in 

 question to which the transmitter had appended the name Sceparnodon ; 

 subsequently the author received, through the kindness of C. H. 

 Hartman, Esq., of Toonromba, Queensland, a large portion of the 

 tooth itself. 



III. " Evidence of a Large Extinct Monotreme {Echidna 

 Ramsayi, Ow.) from the Wellington Breccia Cave, New 

 South Wales." By Professor Owex, C.B., F.R.S. Received 

 November 3, 1883. 



(Abstract.) 



In this communication the author gives a description of a fossil 

 humerus from the breccia cave of Wellington Valley, which repeats 

 the characters of that bone in the existing monotrematous genus 

 'Echidna more closely than those of the same bone in any other known 

 kind of mammal. The fossil, however, greatly exceeds in size that of 

 the existing Australian species, Echidna hystrix, Ciiv. The existence 

 of, at least, two other kinds lately discovered living in New Guinea 

 has been made known in memoirs by Professor Grervais and Mr. 

 E. P. Ramsay, F.L.S. ; these occupy, in respect of size, the interval 

 between them and the Australian Ech. hystrix, but the subject of the 

 present paper makes known the largest Monotreme hitherto discovered. 

 Figures of the fossil in question, and of the corresponding bone of 

 the smaller existing Australian kind, accompany the text. The fossil 

 formed part of the series of remains obtained from the cave above 

 cited, and was with them submitted to the author, who proposes to 

 indicate the present acquisition by the name Echidna Ramsayi. 



IV. " Correction to a paper ' On the Determination of Verdet's 

 Constant,' published in the 4 Phil. Trans.,' 1877." By J. 

 E. H. Gordon, M.S.T.E. Communicated by Professor 

 Stokes. Sec. R.S. Received October 5, 1883. 



(Abstract. ) 



In revising my " Treatise on Electricity " for "the second edition, 

 in July, 1883, I noticed a discrepancy between the value of 

 Verdet's constant obtained by myself and that deduced from M. H. 



