252 PROCEEDINGS OF THE SOCIETY. 



ration arising under such conditions, so that " critical " illumination, 

 with the light converging as nearly as possible upon the centre of the 

 field, was the best available. 



On the motion of the President, a vote of thanks was passed to 

 Mr. Rosenhain for bringing this instrument before them, and for so 

 clearly explaining its construction. 



Mr. Dollman's paper, on " A Method of producing Stereo-photo- 

 micrographs," was read by Mr. Earland, and a number of examples were 

 shown in illustration. 



A paper on " A Simple Method of taking Stereo-photomicrographs, 

 and of Mounting the Prints without Gutting," was also read by Mr. H. 

 Taverner, the subject being illustrated by a drawing on the board and 

 by a number of mounted specimens. 



Mr. Rheinberg said that, as the hour was late, he would not take time 

 by discussing in detail any matters of theory, as regards stereoscopic 

 effects with the Microscope, but he would like to say that he thought 

 Mr. Taverner's simple and practical method of stereo-photography 

 would be found to be one of much value. Though he thought the 

 reason which led Mr. Taverner to use a circular aperture on one side 

 of the objective, in place of using the whole semi-aperture — as had 

 been done by Mr. Dollman and others before — only in small part 

 accounted for the improved effect, he considered there was a very 

 distinct advantage in this innovation. There was an interesting little 

 point of theory involved in it, which seemed so far to have escaped 

 notice, but which it would not be difficult to substantiate at the right 

 time, and which he was hopeful might be turned to advantage in other 

 directions, as well as the one in question at present. 



The President said he had seen some of these photographs, and they 

 were extremely successful and beautiful ; he thought they were very 

 fortunate in having heard these two papers. 



A vote of thanks was then passed to Mr. Dollman, Mr. Earland, and 

 Mr. Taverner. 



Mr. Rousselet said he had received a second list of Natal Rotifers 

 from Mr. Kirkman, amongst which was one new species, Gopeus trian- 

 gulatus, specimens of which were exhibited under a Microscope in the 

 room, and a drawing made by Mr. Dixon Nuttall would be published 

 with the paper in the Journal. 



Mr. Wesche said he had examined the slide, and found this was a 

 marked new form — the two little processes described showed a thickness 

 of skin approaching to the character of a lorica. It was a very interest- 

 ing addition to the fauna. 



The thanks of the Society were voted to Mr. Kirkman for his paper, 

 and to Mr. Rousselet for communicatins: it. 



The President called attention to an interesting exhibition of 

 Oribatidae presented by Mr. N. D. F. Pearce, and shown under a number 

 of Microscopes in the room. 



