4 PRESIDENTIAL ADDRESS. 



OribatId?e (examples of which have been circulated in our boxes 

 by Mr. Bostock and myself), the first volume only of which has as 

 yet appeared. It is by my friend Mr. Michael, and is published 

 by the " Ray Society." It is in all respects an admirable work, 

 well illustrated, and is a model for all would-be workers on mites. 

 The perusal of this book is a great treat in store for those who 

 have not yet seen it. I have myself devoured it with pleasure, 

 for it is a work such as one only meets with very occasionally. 



But we ought to pay more attention to mites, because they are 

 so common, occurring at times almost everywhere : any neglected 

 corner, any stone not recently disturbed, under the bark of any 

 rotten piece of wood, any neglected morsel of food prepared for 

 man or animals, in our entomological cabinets, parasitic on insects 

 of all kinds, birds, mammals, and not sparing man himself, living 

 on his secretions, without causing him much or any annoyance, as 

 in the case of Acariis foUiculoj'um^ or else producing that most 

 troublesome and loathsome disease, known by the very character- 

 istic name of "the itch." Then, again, their external anatomy is 

 so varied and curious, that it necessarily claims much attention 

 from the microscopist. The skin is sometimes smooth and very 

 flexible, plain, or covered with markings like that of our fingers ; 

 at other times, it is formed of chitinous plates of various sizes and 

 shapes like arm.our, and ornamented with markings of different 

 kinds. 



Their very hairs are extremely various, sometimes simple, 

 long, or short ; at other times serrate, like the teeth of a saw, or 

 plumose, like a beautiful feather, sometimes knobbed, at others, 

 flattened out into a scale, and these sometimes like a leaf, and in 

 one case the hairs are like Japanese fans. Their differences so 

 attracted the attention of Hermann a century ago, that he pro- 

 posed their use in the classification of the TroiJihididce. 



The legs are also remarkable for variety in their structure ; 

 sometimes the first pair is scarcely used at all for progression, but 

 act more like antennae or feelers, in some mites being threadlike, 

 and four or five times the length of the body, as in Linapodes ; in 

 other cases, they are remarkably short and stout, and armed with 

 enormous claws, like sickles, as in Disparipes bonibi and Pygme- 

 phorus spinosus. Sometimes it is the second pair that is so 



