Arachnida 20] 



labour of identification is comparatively small. Then the 

 creatures are entirely microscopic that is to say they have to 

 be examined from first to last under the microscope and in 

 this respect they are more convenient to deal with than 

 creatures too large as a whole for microscopic objects, but 

 necessitating microscopic examination of anatomic details. 

 Finally, there are decided advantages in connection with the 

 search for Oribatid mites. Most of them live under bark or in 

 moss and lichen, but their small size makes it almost useless 

 to try and collect individual specimens out of doors, and the 

 best plan is to bring home bags full of moss and pieces of 

 loose bark and to shake them over white paper, when the tiny 

 creatures soon betray themselves by wandering about among 

 the specks of inanimate matter shaken out with them, and the 

 collector can indulge in the pleasures of the chase on his own 

 staidy table with all his apparatus about him. To one who is 

 fond of working with the microscope and is skilful in manipu- 

 lating small objects, the Oribatidae are certain to prove a very 

 attractive group. 



The search during three or four months, and these at the 

 least favourable time of the year, has revealed some forty- 

 five Cambridge species of Oribatidae out of about 100 British 

 species, and these are divided among fifteen genera. In size 

 they range from something over a millimeter to '3 mm. Some 

 of them are extremely elegant in form, while anything more 

 grotesque than others it is difficult to imagine. 



Most of the species so far discovered belong to the genera 

 Oribata and Nothrus. Mites of the genus Oribata are round 

 or oval, with hard polished integuments, which have given to 

 the group the popular name of beetle-mites. About a dozen 

 species are already included in the local fauna. The genus 

 Nothrus is very different in appearance. The integuments 

 are leathery and rough, and often bristling with the oddest 

 array of protuberances and spines. Six species have been 

 recognised in the neighbourhood of Cambridge. 



