626 



IVAR TKAGArDH 



fold runs across in an even curve backwards. The anterior median part at 

 the base of the pseudocapitulum has the cuticle finely reticulated by very 

 minute, semispherical projections which are arranged in transverse rows. By 

 means of this structure the pseudocapitulum seems to be capable of being 

 retracted and protruded, as is probably the case in B. antarcticum Tragardh, 

 which has a quite similar structure. 



The crista metopiea does not end in any well defined anterior area 

 sensilligera, but is linear and has only at the posterior end a rather indefined 

 area. It extends backwards to a level with the posterior eye-shaped structures. 

 The anterior tactile hairs are flanked by two pairs of straight, blunt bristles 

 which are about 3 times as big as the body hairs. 



Eyes. As pointed out above, there are two pairs of eye-like structures, 

 but a lens is only developed in the anterior pair, where it is very highly 

 convex. 



Mouthparts (fig. 165). The palps: ist joint very short, slightly curved 

 and clavate, with 3 straight paralell bristles in the anterolateral angle; 2nd joint 

 large, longer than the 3rd joint and twice as long as it is high, with convex 

 dorsal and almost straight ventral edge, with 4 6 long, straight bristles sub- 

 marginally and ventrally on the exterior side, 6 — 8 curved hairs dorsally and 

 marginally and a similar number on both sides; 3rd joint curved very sharply 

 downwards at the base, the basal portion being concealed within a fold at the 

 top of the 2nd joint; 3rd joint — except for the curve at the base — straight, 

 3 times as long as it is high, and scarcely half as high as the 2nd joint, with 

 numerous, short, slightly curved hairs; 4th joint very short, with fairly slender 

 and slightly curved claw; 5th joint narrow, of uniform width, rounded at the 

 top and exactly as long as the claw, with 7 8 small hyalin hairs on the ventral 

 side and at the top. 



The size and the proportions of the legs is seen in the accompanying 

 table. The tarsi and the top of the tibia have a structure which is of special 

 interest (fig 166). The dorsal part of the anterior edge of the tibia is shaped 

 as a kind of condylus and the corresponding part of the base of the tarsus is 

 deeply excavated like a socket. In this way it is possible for the mite to 

 bend the tarsus upwards at a right angle, an acomplishment which may be of 

 some use during its locomotion. 



Loc: Juan Fernandez, Masatierra. 



