A CARINA, OR MITES. 



Order ACARINA, or MITES. 



93 



An easilyobserved distinction in structure between the scorpions, 

 spiders, and mites, is, that the latter never have their abdomen 

 segmented like the scorpions, nor pedunculated (that is, joined to 

 the body by a narrow point of attachment) like the spiders. It is 

 always in one piece, and united without any well-marked groove 

 of separation to the last of the segments that bears the legs. 



As a rule all mites have eight legs when mature, some indeed 

 have their posterior legs atrophied and apparently absent, but 

 traces of them can always be discovered, or their absence is an 

 exceptional peculiarity. In their earlier stage they all have six. 

 This statement may be made with confidence, for numerous 

 species in every section and in almost every genus have been 

 reared or observed, and in every instance the young were hexa- 

 pod. The only apparent exception is the Phytopti, which in all 

 stages appear to have only four, the two hinder limbs being ab- 

 sent ] but, as we shall hereafter show, even this is in all proba- 

 bility only an apparent exception, not a real one. 



The following is the arrangement which we propose for this 

 order. It is very nearly the same as that generally adopted by 

 naturalists, some few modifications, which recent researches seem 

 to have rendered necessary, only having been made. 



1. Trombidiin.^, containing — 



1. Tetranycht, spinning mites. 



2. TROMBiDiiDAi, harvest mites. 



2. BDELLiDyE, snouted harvest mites. 



3. Hydrachnid^, water mites. 



4. GAMASiDi^, insect mite-parasites. 



5. IxoDiD^, ticks. 



6. Halacarid^, marine mites. 



7. Oribatid/e, beetle mites. 



8. AcARiD^ : — 



1. Hypoderid/e, subcutaneous 



mites. 



2. HypopiD/E, ichneumon mites. 



3. Tyroglyphid^, cheese mites. 



4. Sarcoptid^, itch and louse 



mites. 



5. Phytoptid^, gall mites. 



We shall not go into any minute scientific description of the 

 characters of these different mites ; but they have hitherto been 

 so little studied in this country that we feel sure we shall 



