58 PROCEEDINGS OF SOCIETIES. 



the object. Another, also imperfectly printed, and magnified 3000 

 diameters, shows short, abrupt, strongly-defined shadows, sup- 

 porting, as it were, the areas — an effect produced probably by 

 interference at the junction of the hemispheres. This print 

 should be examined and compared with another of Pleurosigma 

 formosum, which shows the valve under various powers from 

 700 up to 3000 diameters. There is a small bit of print on 

 this card which is remarkable and valuable to those particu- 

 larly interested in resolving markings. The print of P. ancju- 

 lafum presents some interesting points as to its structure. Some 

 of the areas appear quite round, not hexagonal ; bright angular 

 points separate these nodules in the one case, converting 

 them into divisional lines in another ; and the curious point 

 is, they are both from the same negative. With regard to this 

 plate, Dr. Maddox observes that " the negative was a foil ore from 

 the plate being dirty;" nevertheless it is very instructive in 

 various points. The larger prints exhibuted should be regarded 

 rather as pictures than representations of the sharp outline 

 figures seen in the microscope. 



Nov. Y^tTi, 1867. 



James Glaishee, Esq., F.E.S., President, in the Chair. 



The minutes of the previous meeting were read and con- 

 firmed. 



The following presents were announced and thanks voted — 



Presented hy 



A Four Inch Object Glass • , . T. Ross, Esq. 



Hog-g on the Microscope, Sixth Edition . . The Author. 



Quarterly Journal of tiie Geological Society . . The Society. 



The Journal of the Society of Arts. 4 Nos. . , Ditto. 



Acta Universitatis Lundineusis. 3 Parts . . Ditto. 



Katural History Transactions of North Durham . Ditto, 



lutellectual Observer .... The Publisher. 



Certificates in favour of the following gentlemen were ordered 

 to be suspended : 



George Potter, 7, Montpellier Road, Upper Holloway ; Richard 

 Bannister, Inland Revenue Laboratory, Somerset House; P. Thos. 

 Baker, 184, King's Eoad, Chelsea, S.W. ; Henry Owens, M.D., 

 Croydon, S. ; William Thomas Loy, Dingwel'l Eoad, Croy- 

 don, S. ; the Eev. Frederick William Eussell, M.A., Charing 

 Cross Hospital ; the Eev. Francis Pigou, M.A., 14, Suffolk 

 Place, Pall Mall East ; James Murie, M.D., Zoological 

 Gardens, Eegents Park; John Mayall, 224, Eegeut Street; 

 James J. Simmons, 18, Burton Crescent, AV.C. ; Thomas Wilcox 

 Edmunds, 32, Old Change ; Frederick Ciarkson Francis, 9, 



