508 
CLASS ARACHNIDA. 
of eyes varies from two to four, and goes even as far as six, 
according to Muller. 
The mouth of the species, which I have studied, presents 
the three following modifications, which have served as bases 
for three generic sections, but to which it is impossible to 
refer all the species of Muller’s Hjrdrachnse, this naturalist 
not having described them with sufficient detail. 
Eylais, Lat ., 
Which have antennae- pincers, terminated by a mobile hook. 
Hydrachna, Lat ., 
Whose mouth is composed of laminae, forming an advanced 
sucker, and whose palpi have under their extremity a mobile 
appendage. 
Limnochares, Lat., 
Similar to hydrachna, in the sucker-formed mouth, but whose 
palpi are simple. 
Other Mites, Microphtiijra, Lat., are remote from all 
the other aranchnides, by the number of feet, which is only six. 
They are all parasite. 
Caris, Lat., 
Which have a sucker and apparent palpi ; the body rounded 
very flat, and clothed with a scaly skin. 
Leptus, Lat., 
Having also a sucker, and apparent palpi, but whose body is 
very soft and ovoid. 
L. Autumnalis, Acarus Autumnalis, Shaw r , Zool., Misc. 
t. II. pi. xlii., a species very common in autumn, on gra- 
mineous and other plants. It climbs and insinuates itself 
