450 



Prof. P. M. Duncan on Guynia annulata. [May 4, 



[From a general recollection of a conversation I had with Sir W. Thom- 

 son before the presentation of his paper, I do not imagine his object to 

 have been exactly what the Astronomer Royal here describes, but partly the 

 saving of trouble in numerical calculation, partly the exhibition, for each 

 separate observation of altitude at a noted chronometer time, of precisely 

 what that observation gives, neither more nor less, which introduces at the 

 same time certain facilities for the determination of a ship's place by a 

 combination of two observations. Of course the place so determined is 

 liable to an error east or west corresponding to the unknown error of the 

 chronometer ; and doubtless, under ordinary circumstances, this forms the 

 principal error to which the determination of a ship's place is liable. This 

 remains precisely as it did before ; and it is hard to suppose that the mere 

 substitution of a graphical for a purely numerical process could lead a 

 navigator to forget that he is dependent upon his chronometer, though 

 perhaps the general tone of Sir W. Thomson's paper might render an 

 explicit warning desirable, such as that which Mr. Airy supplies. — G. G. 

 Stokes.] 



May 4, 1871. 



Sir PHILIP GREY-EGERTON, Bart. ; Vice-President, in the Chair. 



In conformity with the Statutes, the names of the Candidates recom- 

 mended for election into the Society were read from the Chair, as 

 follows : — 



William Henry Besant, M.A. 

 William Budd, M.D. 

 George William Callender, F.R.C.S. 

 William Carruthers, Esq. 

 Robert Etheridge, F.R.S.E. 

 Frederick Guthrie, B. A. 

 John Herschel, Capt. R.E. 

 Alexander Moncrieff, Capt. M.A. 



Richard Quain, M.D. 

 Carl Schorlemmer, Esq. 

 Edward Thomas, Esq. 

 Edward Burnet Tylor, Esq. 

 Cromwell Fleetwood Varley, C.E. 

 Arthur Viscount Walden, P.Z.S. 

 John Wood, F.R.C.S. 



The following communications were read : — 



I. "On the Structure and Affinities of Guynia annulata y Dune, 

 with Remarks upon the Persistence of Palaeozoic Types of Ma- 

 dreporaria." By P. Martin Duncan, M.B. Loud., F.R.S., 

 Professor of Geology in King's College, London. Received 

 March 16, 1871. 



(Abstract.) 



The dredging-expedition which searched the sea-floor in the track of the 

 Gulf-stream of 1868, yielded, amongst other interesting Madreporaria, a 

 form which has been described by Count Pourtales under the name of 



