THE ACARINA OE MITES. 



125 



which has considerable resemblance to the female and the other which has several 

 secondary sexual characters, the anterior paii's of legs being long and hea\'y and^the 

 immovable finger of the mandildes being greatly enlarged and lengthened. There 

 is, however, an hypopial stage in the life of this mite wMch has been the theme of 

 much discussion among acarologists for many years. This hypopial form was de- 

 scribed in 1861 by Filippi as Hypodectes and by Nitzsch as Hypoderas (fig. 250). 

 Eypodectes is found in various parts of the internal anatomy of bii'ds, generally in the 

 areolar and peritracheal tissues. It is of an elongate form, rounded in front and 

 behind, and with eight short legs, two pairs in front and two other pairs toward the 

 posterior end. There are no mouth organs, and Slosarsky, who examined the anat- 



b 



Fig. 257. 



-Allanalges gracilcpinnatus. (Author's 

 illustration.) 



Fig. 258. — PtcTodcctes armatus 

 (Original.) 



omy, found no internal structures save a few muscles attached to the legs. From 

 this it was evident that Hypodectes was a nymph in the state of histolysis. Mcgnin 

 Boon made a more extended study and found that the mite was a stage in the life 

 history of a Pterolichus (now placed in the genus Falculifer). Megnin considers 

 that when the Faculifer finds that it is being deprived of shelter and food by the 

 birds pulling out their feathers, certain normal nymphs transform into the hypopial 

 Hypodectes. This then crawls into the respiratory organs, or into the liair follicles, 

 burrows some distance, and there remains until normal conditions are reestablished, 

 when it reappears on the outside. However, it is probable that more is to be learned 

 regarding these subcutaneous forms. In this country Hypodectes has been taken 



