8 PRESIDENTIAL ADDRESS. 



where they re-assume then- previous condition of nymph, complete 

 the cycle of their development, and give origin to new colonies. 



The Sarcoptidce^ or Itch Mites, forming the next family, include 

 the AnalgificB, or Bird-Louse Mites, a singular and very imper- 

 fectly worked-out group. Living amongst the feathers of birds, 

 and feeding upon the effete matters falling therefrom, they pro- 

 bably cause little or no inconvenience to their hosts. The forms 

 are both varied and remarkable, especially upon some foreign 

 birds, and they offer a large and interesting field of study to any 

 microscopist inclined to enter upon it. 



The Sarcoptwce, or Itch Mites proper, are not an inviting 

 subject, or one upon which I can any longer dwell, beyond 

 remarking that I have but rarely met with any single rat in which 

 the ears were not infested with Sarcoptes miita7is^ a form closely 

 allied to scabiei. 



The Arctisco7iidce and Demodicidce present few points of general 

 interest, so with a passing reference to the last family of Phytopti^ 

 I will now close. They are found upon the leaves of various 

 trees and plants, producing excrescences of different forms and 

 characters. It is uncertain whether they are miniature forms of 

 Tetraiiychi or not. And here we have another field for investiga- 

 tion well worthy of being worked out. 



If by directing attention to these small creatures any of our 

 members are led to take a greater interest in the subject of my 

 address, they cannot fail to derive much pleasure and instruction 

 from the investigation of their habits and modes of life, or to be 

 struck by the marvellous variety and perfection impressed by the 

 hand of the Creator upon these minute living atoms ! 



The Coldest Region. — According to the Russian meteor- 

 ologists, the coldest spot yet found upon the earth is Werchojansk, 

 in Siberia, where an observing station of the government has 

 been established. The mean temperature there, for the year 

 1885, was 2-9*^ Centigrade below zero. For the month of 

 January of that year it was 62 -qC. below zero, but for July it 

 rose to 6o'6C. above zero. The lowest in July was 39'2C. above 

 zero ; and in January the thermometer fell as low as 88-6C. 

 below zero. 



