ANATOMY. 55 



truncated at tlie distal end, and with the truncated 

 end toothed, and more or less chitinized. These are 

 usually called the maxillae, and are highly developed 

 in the genus Hoplod&rma (formerly called Hoplophora, 

 which name is, however, preoccupied) ; there the 

 maxilla3 have every appearance of being functional. 

 In the Tyroglyphidas the maxillary lip and maxillae 

 are of the Oribatidae type; but the fusion is greater 

 than in that family, and these organs are not nearly so 

 highly chitinized ; indeed they are usually so soft and 

 transparent that it is difficult to believe that they have 

 much, if any, biting or crushing functions; still the 

 form of the Oribata maxilla is, as a rule, clearly 

 traceable. Good examples of this formation are Glycy- 

 l>!i<jnx Caitestrinii (PL XI, fig. 10), Glycypliacjus platy- 

 gaster (PL XIV, fig. 6), and Tyroglyphus siro (vol. ii). 



The Maxillary Palpi, which are the only palpi, 

 spring from small shoulders, or notches, one on each 

 side of the maxillary lip ; they are not active, con- 

 stantly moving organs like the corresponding parts 

 in Gamasidae and Oribatidae, nor are they the strong 

 raptorial palpi of Cheyletm or Trombidium ; they lie 

 along the lateral edges of the maxillary lip, the distal 

 joint only being frequently turned downward : they 

 usually consist of three free joints only ; the proximal 

 being the longest and thickest ; except in Histiostoma ; 

 in some species this joint also shows more or less 

 tendency toward fusion with the Hypostome. I am 

 inclined to think that these appendages may probably 

 be regarded as derived from a five-jointed palpus, such 

 as that of the Oribatidae, the trophi of which have so 

 strong a resemblance to those of the Tyroglyphidas in 

 most other respects ; the basal joints having become 

 fused, either with the proximal free joint or the 

 maxillary lip ; indeed, in Lentungula the five joints 

 may be traced. The principal other appendages, i. e. 

 the legs, have five free joints in both of the families. 

 The joints are usually cylindrical, or some approach to 

 that form, often narrowing a little toward their ends ; 



