12 ARKIV FÖR ZOOLOGI. BAND 2. N:0 8. 



tarides the lower surface of both pairs is found nearly in t lie 

 same horizontai plane. Furthermore, in Oxopoei the sternal 

 plate mentioned is anteriorly at the middle produced into a 

 short blunt triangle, and each half of its anterior margin is 

 emarginate; in the whitish membranous transverse skin be- 

 tween the large sternal plate and the mandibles is seen a 

 transverse chitinous strip which is curved backwards in the 

 middle and here equipped with some setae, three of whicli are 

 very long, hidden in the narrow furrow between the man- 

 dibles. 



We believe that in all Uropygi the chitinized elements 

 bearing these setse in the membrane between the large sternal 

 plate and the mandibles are a rudimentary labium. 



In all Uropygi each of the two thoracic segments has a 

 sternum of its own. In both tribes the sternum of the first 

 thoracic segment is a linear strip (fig. le, g), that of the 

 second segment is a trapezium (r), the shortest side of Avhich 

 is placed near the front margin of the foiirth pair of coxae. 



The foiir Pairs of Walkiiig' Legs. — In the two tribes 

 of Uropygi the walking legs agree in many respects, but some 

 sharp differences are yet to be found. All four pairs consist 

 of coxa, trochanter, femur, patella, tibia, metatarsus and 

 tarsus; but the first pair differs much from the three others 

 which show a rather close mutual conformity. The coxse of 

 these three pairs (Pl. 1., fig. 1 c) originate very near the 

 middle line, those of fourth pair yet a little longer from that 

 line than the two other pairs; this position which conse- 

 quently corresponds with the shape of the sternum, differs 

 sharply from that met with in Amblypygi or Araneae, as the 

 basal ends of the coxse of the same half are placed in a concave 

 line in Uropygi and in a convex in the two other divisions. 

 These coxa? are robust and movable; in Oxopoei they are 

 a like and nearly of the same length, in Tartarides those of 

 the first pair (Pl. 1., fig. 1 c, k) are longer than the two other 

 pairs, and their anterior distal angle is produced into a narrow 

 acute process. In these three pairs of legs patella is in Tar- 

 tarides long in proportion to tibia, shorter but yet good-sized 

 in Oxopoei. In Tartarides (PL 2., fig. 1 e) metatarsus is long, 

 nearly as long as tibia and longer than tarsus; in Oxopoei 

 metatarsus is very short, even shorter than the proximal 



