PROCEEDINGS OF SOCIETIES. 63 



and Hartnack' s No. 11 immersion lens ; the object being the 

 Podura scale, and the diameters 2100 and 756. lu the foremost 

 rank, in Dr. Maddox's opinion, stood Powell and Lealand's 3-Vtli ; 

 then Wales' ith and amplifier; Wales' -^^th immersion; and 

 Powell and Lealand's ^V^'^* Hartnack's did not give a good 

 image photographically : but as Dr. Woodward, in a private 

 letter to Dr. Maddox, remarked, this might have depended on 

 the great want of coincidence of the visual and chemical rays, as 

 it had to be "ruled out" considerably; but Dr. Maddox seemed 

 to think it might be due to some trifling error in the centring, 

 when the necessary chemical correction was made. Dr. Maddox 

 said he believed the Podura scale hud never yet, in this country, 

 been photographed by a 55th. 



The series of twenty photomicrographs were greatly admired, 

 especially a Navicula rliomhoides, magnified more than 800 dia- 

 meters, and taken with Wales' \i\\ and amplifier. 



The Fellows of the Society felt themselves highly gratified 

 with tlie opportunity of examining the excellent results that had 

 been placed before them. 



Mr. Slack exhibited an ingenious lamp, made by Mr. Collins, 

 and devised by Mr. Beckett. Mr. Highley had been the first, 

 many years ago, to construct lamps so shaded that no light was 

 allowed to escape except in the direction required for microscopic 

 use. Mr. Bockett carried out the same idea by means of a para- 

 bolic silvered reflector and a dark screen. All the rays from this 

 lamp were emitted straightforwards, in approximately parallel 

 rays. Such a plan would eff'ectually screen the eyes of an ob- 

 server from extraneous light. 



In reply to an inquiry, Mr. Collins said the parabolic reflector, 

 without the lamp, would cost about *ls. %cl. 



Mr. Bkowning remarked that, with such a reflector, it was 

 highly necessary to correct the increased amount of the yellow 

 ray, by using a blue chimney, as Mr. Bockett had done. 



The following papers were read : 



" On the Anatomical Diff"erences observed in some Species of 

 the Helices and Limaces," by Edwin T. Newton, Esq. (See 

 'Trans.,' p. 26.) 



" On New Species of Microscopic Animals," by T. Gr. Tatem, 

 Esq. (See 'Trans.,' p. 31.) 



The usual vote of thanks was passed to their respective authors ; 

 and the President announced that at the next meeting, January 

 8th, Professor Eupert Jones, P.G.S., would read a paper "On 

 Recent and Fossil Bivalved Entomostraca." 



Errata. — The errors iu reference to some of the fifrures named in the text in 

 Dr. Maddox's paper on " Parasites of the Coinnion Haddock," not correspond- 

 ing with those in the plate, arises i'rom all the illustrations sent not being 

 engraved. It is necessai-y to erase references to figures on pp. 88, 90, and 92. 



