64 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXVIII. 



Tho <4-enus /J/'/n/dius is peculiar in having- enormously long extensile, 

 llexil)Ie niandihlos. The mandibles are more than twice as long as tlie 



entire animal, and can he retracted so that 

 the bend in them is close against the poste- 

 rior walls of the abdomen. The tips of 

 these mandibles are distinctly chelate. We 

 have one species in this country. 



From New Guinea, Canestrini has de- 

 scribed several species of a remarkable 

 genus — Der(/Joj>/iorus. The}' have a pair 

 of plate-like projections over the head, and 

 from these arise long bristles, and there are 

 also bristles at tip of abdomen. Two other 

 genera, Vi-opodeJla and Fcdrtzzia^ have 

 been described from tropical countries. 



Superfamily ORIBATOIDEA. 



The Oi'it)atid mites may usually be recog- 

 nized l)y the presence of a single character, 

 a hair or seta arising from a small pore 

 near each postei'ior corner of the cepha- 

 lothorax. This pore was formerly con- 

 sidered a spiracle, ])ut it is now known not 

 to be such. Its function, however, is un- 

 certain, and it is called a pseudo-stigmata, 

 while the hair arising therefrom is known as th(^ pseudo-stigmatic 

 organ. . 



With tho great majority of the Oribatidje the tegument is coriace- 

 ous: it is because of this that these mites have been called '"beetle 

 mites.'' This name is some- 

 what misleading, as members 

 of another family, the Gama- 

 sidie. are often attached to 

 beetles, and therefore some- 

 times termed "l^eetle mites.'' 



The body of an Oril)atid is 

 short, broad, and usually high. 

 There is always more or less in- 

 dication, usually very plain, of 

 the division into cephalothorax 

 and nl)domen. There is at this 

 point a constriction on the sides, 

 a line or suture on the venter, 



and a break in the continuity of the dorsal outline. The posterior pairs 

 of legs are apparently attached to the abdomen. The coxi\? of the legs 



Fig. 119.— Le(;, m.^ndible, and 

 pseudostigmatic organ' of 



AN' ORIBATID. 



Fig. 120.— Hoi'i,oi>er.ma i^rnjiRULA. 



