CHAPTER IV. 



UPON THE CLASSIFICATION OF THE TYEOGLYPHID^E. 



PROBABLY the earliest thing which can be in any way 

 considered as an attempt to classify the Tyroglyphidae 

 was that of C. L. Koch in 1842;* although in this 

 place Koch does not call the creatures TyroglyphidaB, 

 and does not treat them as a family ; he calls them the 

 two genera AGO/TUB and Homopus, and includes them 

 in the Sarcoptidge ; but he says " the species of the 

 genus Acarus are rendered somewhat remote from the 

 other genera by their mode of life ; they are not found 

 on living creatures ; they cannot remain in the present 

 family." 



The genus Homopus is bad in two ways; firstly, 

 because it is founded on an immature (Hypopial- 

 nymphal) type, and depends entirely upon the immature 

 condition ; and secondly, because the name Homopus 

 was preoccupied, having been used by Dumeril and 

 Bibron t for a genus of reptiles in 1835. 



Koch divides his genus Acarus into sections, as 

 follows : 



A. Cephalo thorax and abdomen melting into one 

 another. The tarsi thin, needle-shaped; the other 

 joints with thick setiform or spine-like appendages. 

 The body-hairs simple. 



B. The cephalo thorax plainly marked off, the body- 

 hairs simple, the legs finely haired, the tarsi a some- 

 what thicker needle-shape than in A. 



C. Cephalothorax and abdomen not divided from 

 each other ; body-hairs feathered. 



* ' Uebersi,' Heft 3, pp. 118121. 

 f Erpetologie. 



