NOTICES OF NEW BOOKS. 77 
the Oribatide, whereas this creature belongs to an entirely 
different family, viz., the Gamaside. 
The name of “ beetle-mite” has no doubt been given from 
the general resemblance in appearance of many, indeed most, of 
the species to beetles. This resemblance is, however, probably 
little more than superficial, as in most essential points the 
Gamaside are more closely allied to the true Insects than the 
Oribatide, the first pair of legs being true walking legs in the 
Oribatide, and not used for any other purpose, whereas in the 
Gamaside they are usually tactile organs, little, if at all, used for 
locomotion, and, although pediform in shape and size, they are 
really more closely allied to palpi, and are placed in close 
proximity to the mouth organs. 
The term Oribatide, from oribata, is, as Mr. Michael remarks, 
euphonious, but we fail to see its applicability, except upon the 
lucus a non lucendo principle, since it is derived from the Greek 
words ogos, a mountain, and faiw, I go. Seeing the rate of 
progress at which these tiny creatures travel, the ascent of a 
mountain would be more than a life-long task. It is possible, as 
Mr. Michael suggests, that Latreille, the proposer of the name 
Oribata in 1804, may have based it not directly upon dgos and 
Baiva, but upon the proper name Oribasus, Acteeon’s dog, derived 
from these two words. At any rate Oribata is the name which 
has come to be universally employed for these Acarids, to the 
exclusion of Hermann’s name Notaspis, bestowed the same year. 
The Oribatide are all of microscopic size, the largest species 
known being not more than the twentieth of an inch in length, 
while the smallest are under a fifth of that measurement. It will 
be readily understood that this very small size renders it 
extremely difficult to ascertain their structure or to study their 
life-histories, particularly as they possess in the adult stage a 
chitinous exoskeleton of unusual brittleness, and often go black 
and rough that a very high concentration of light is necessary to 
see them properly, while the necessity for using moderately high 
amplifying powers renders strong reflected light more difficult to 
obtain ; and moreover strong light is most unwelcome to the 
creatures, almost all of which live in comparative darkness, and 
avoid the light as much as possible. 
These and other difficulties, however, Mr. Michael, by un- 
wearied patience and careful manipulation, has contrived to 
