48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



Trochantin. — The trochantin (fig. 26, Tr) is a small structure and 

 is closely attached to the femur. On the ventral or outer side, when 

 the femur is kept close to the body, a deep groove, the trochantero- 

 femoral groove (a) separates the femur from the trochantin. On 

 the dorsal, or inner side, the separation is indicated by a suture only. 

 Structurally, three parts may be distinguished on the trochantin. 

 These are the basicostal ridge (b), the articulatory condyle (c) and 

 the small apical piece (r). The basicostal ridge is a broad, stuffed, 

 ringlike structure which gives the articulation with the coxa an ex- 

 ternal rest. For the same purpose a hooklike process on the postero- 

 median angle of the basicosta is used. The prominent, cone-shaped 

 articulatory condyle originates basally. The shape of the condyle is 

 alike in all three pairs of legs; the slight differences showing in the 

 plate are due to the different angles from which the drawings were 

 made. The apical piece projects over the basicosta when viewed from 

 above, dorsally, and is fused with the basicosta when seen from below. 

 It bears a long slender spine in all three pairs of legs. The basicosta 

 is externally armed with a few small hairs. From the kind of con- 

 nection between the femur and the trochantin it can be concluded that 

 but little movement is possible between them. 



Femur. — The femur (fig. 26, F) is the strongest segment of the 

 leg and is about equal in length with the tibia (Ti). Basally it is con- 

 nected with the trochantin ; apically, the tibia articulates. The femur 

 is long, oval to rectangular in outline and strongly compressed. The 

 articulation of the tibia is bicondyle (d, e), the femur containing two 

 half circular fossa. There occur no striking differences in the three 

 examined species or in the three pairs of legs in one species. The 

 inner or dorsal surface of the femur is smooth without hairs or 

 bristles ; the exposed surface bears numerous rather fine, long hairs 

 which are directed transversely. A deep groove (f ) with two lateral 

 winglike extensions occurs latero-apically. This groove allows the 

 tibia to be flexed closely against the femur. 



Tibia. — The tibia (fig. 26, Ti) is about as long as the femur, tri- 

 angular in outline and strongly compressed anteriorly. The proximal 

 end is widened, half circular in outline, and bears the two articulatory 

 condyles. The proximal quarter of the tibia is slightly bent laterally. 

 The dextral margin is without teeth or armations ; the sinistral margin 

 bears four to six low serrations and three marginal teeth (i) which 

 are imbedded in sockets. The apical tooth (j) is straight, rather stout 

 and not imbedded in a socket ; the subapical tooth is present as a low 

 elevation only. The articulation of the tarsus is membranous. 



