26 



November 12th, 1886. — Conversational Meeting. 



The following objects were exhibited : — 



Uroceni rum turbo Mr. F. AY. Andrew. 



Diatoms from Oamaru ... ... Mr. A. Cottam, 



Mr. F. Enock. 



Crenulate antenna of Moth ... ... ~) 



Pygera Lucephala, natural form and colour ) 



Human retina, normal ... ... ... ... Mr. G. C. Karop. 



Pyrgodiscus simplex ... ... ... ... Mr. H. Morland. 



Navicula disciformis, with \ apochromatic "^ jj- -^ ,»- w e i aon 



object glass ... ... ... ... } 



Fredericella sultana ... Mr. C. Le Pelley. 



Zoothaninium arbuscula... ... ... ... } , ,, 



Anthodiscus floreatus (G. & S.), n.s. from j -V ^ gturt 



Oamaru... ... ... ... ... J 



Atttendance — Members, 35 ; Visitor, 1. 



November 26th, 1886. — Ordinary Meeting. 

 A. D. Michael, Esq., F.L.S., F.E.M.S., President, in the Chair. 



The minutes of the preceding meeting were read and confirmed. 

 The following additions to the Library were announced : — 



" Annals of Natural History " ... ... ... Purchased. 



" British Desmids," Part V. ... ... ... „ 



" British Petrography " ... ... ... ... „ 



" The Rotifera," Part VI. ... ... ... ... „ 



" The Botanical Gazette " ... ... ... ... In exchange. 



" Proceedings of the Geologists' Association "... „ 



The Secretary annonnced that the second part of Mr. Sturt's paper " On 

 Diatom Structure" had been received, and would be taken as read that 

 evening. 



Mr. E. M. Nelson read a paper " On the New Apochromatic Lenses," in 

 the course of which he explained, by the aid of diagrams, what was meant 

 by the " secondary spectrum," which was said to be got rid of by the use 

 of the glass of which these combinations were constructed. 



Mr. Nelson also read a further paper " On a Method of Finding the 

 General Character of a Cemented Combination," the subject being largely 

 illustrated by means of diagrams. 



Mr. John Mayall, jun., inquired if Mr. Nelson had, by any chance 

 attempted to estimate the forms adopted by Zeiss in the new apochro- 

 matic objectives, so as to get an approximate idea of the combinations ? 



