10 ARKIV FÖR ZOOLOGI. BAND 2. NIO 8. 



A real lahium is wanting; what we consider to be the 

 vestige of the labium is described below in the paragraph on 

 sternum. 



In Oxopoei the mandibles show a similar form and struc- 

 ture, but they are shorter and broader, and the junction be- 

 tween them in the mesial line is proportionally longer and 

 more firm; labrum is thicker and more copiously clothed with 

 hairs; in other respects the structure is essentially alike that 

 in Tartarides ^ 



Mandibular Palps (maxillary palps, auctorum). (Pl. 1., 

 fig. 1 k). — They consist of a trochanterial (6), a femoral (c), a pa- 

 tellar (d), a tibial (e), and a tarsal part (/) furnished with a 

 strong claw {g); they are inserted so that they are folded 

 in the vertical plane. In Oxopoei they are folded mainly in 

 the horizontal plane; the inner distal portion of the tibial 

 part is produced into a strong, triangulär process, the tarsal 

 part is claw-shaped — a real claw is wanting in this tribe as 

 always is the case, when the palp terminates in a chela — 

 proportionately slender, and can be bent against the tibial 

 process, both together constituting the two fingers of the 

 chela. In Tartarides the palp does not terminate in a chela, 

 and the tibial part has no distal process against which the 

 tarsal part could be moved; the tarsal part is conical, trun- 

 cate, on the lower side near the end with a couple of small 

 conical processes (Pl 1., fig. 1 1, p), and terminates in a good- 

 sized movable claw. In Tartarides the trochanterial part has 

 on the lower side a nearly axe-shaped expansion directecl 

 downwards and more or less forwards, for which reason the 

 femoral part is articulated to its upper side; in Oxopoei the 

 expansion is directed inwards and forwards, and the femoral 

 part is fixed on the outer side of the trochanterial one. The 

 difference in the position of the palps between the two tribes 

 is therefore due to their articulation on the coxal part, the 

 mandible (Pl. 1., fig. 1 k, a.) 



^ It may be nientioned that tho mandibles and the structure of the 

 mouth in Uropvgi have been dealt with by R. I. Pocock (Proc. Zool. Soc. 

 June 17, 1902)^ and C. Eörner (Zool. Anzeiger, Bd. XXVI. Dec^ 190J): 

 Pocock nientions the structure in Oxopoei, Börner in both tribes oi Uropygi. 

 We refer to these publications, without entering into any abstract or cri~ 

 ticisrn. 



