PROCEEDINGS OF THE SOCIETY. 255 



nation was obtained with improved definition, so that the contour of 

 blood corpuscles, for instance, could be seen in a way which could not 

 be obtained with ordinary illumination. Accessory mechanism enabled 

 a camera to be fitted to the arrangement. One use of this method was 

 to get a really dark ground with high magnification, but a still more 

 valuable result was the strengthening of the definition in a bright field 

 without reducing the angle, and consequently without loss of resolving 

 power. 



On the motion of the Chairman, the thanks of the Society were 

 unanimously voted to Mr. Gordon for the exhibition of his very 

 ingenious contrivance, and for the explanation of it which he had given. 



Mr. C. F. Rousselet read a paper entitled, " A Contribution to our 

 Knowledge of the Rotifera of South Africa," illustrating the subject by 

 a large number of lantern slides of the organisms described, and of the 

 localities whence they were obtained, as well as by specimens exhibited 

 under Microscopes in the room. 



The Chairman, in moving a hearty vote of thanks to Mr. Rousselet 

 for his communication, said he was sure all present would be glad to 

 join in expressing their appreciation of the very interesting account 

 which Mr. Rousselet had given of his trip to South Africa, and of the 

 excellent photographic illustrations which he had shown to them of the 

 places he had visited. 



Mr. Joseph M. Coon exhibited and described a new form of finder,, 

 which could be used on any Microscope and with high powers, a special 

 feature of the apparatus being that an object registered on one Micro- 

 scope could be found on any other. The contrivance was shown in use 

 attached to several Microscopes, and was further explained by drawings 

 on the blackboard. 



The thanks of the Society were voted to Mr. Coon for his interesting- 

 exhibition and explanation. 



Mr. N. D. F. Pearce's paper on " Some Oribatidas from the Hima- 

 layas," was read by the Secretary. 



Mr. A. D. Michael said this was a very interesting paper, because we 

 had hitherto known absolutely nothing about the Oribatidae of Sikkim, 

 and very little indeed of those found in the tropics. The wide distribu- 

 tion of these creatures was very remarkable, considering that they were 

 so very slow moving, living chiefly in mosses and similar kinds of 

 vegetation, for in searching material from various parts of the world, he 

 had generally found British species among them — and in the paper 

 before them there were no widely different types from those found in 

 England at the present day. A less careful observer might have classed 

 many more of them as British species, but the author had picked out 

 minute differences with great skill, although the differences were not in 

 any instance very wide. To get any record at all was very interesting, 

 for Sikkim was a luxuriant and gloriously situated district lying between 



