NO. 13 STAPH YLINIDAE BLACK WELDER 39 



the anterior and one on the posterior face. Those of the posterior series 

 (fig. 8 E) are longer and more slender than those of the anterior series 

 (fig. 8D), but the latter series contains more setae (about 12) and 

 extends farther across the tip. The main part of the tibia bears two 

 types of setae. The most conspicuous is the large thick and blunt 

 setae similar to those of the terminal series but shorter and some- 

 what more regular in outline. They occur scattered sparsely on the 

 posterior aspect, there being perhaps 15 in all, but there are none on 

 the anterior face. The other type is the smaller tapering setae which 

 form the normal vestiture. They are sparse on the posterior aspect, 

 none occurring close to the proximal end, and they approximate the 

 length of the larger terminal series on the distal portion, being gradu- 

 ally smaller toward the base. The anterior aspect and the dorsal 

 portion are clothed with these finer setae similarly to the posterior 

 face, but the ventral aspect of the tibia is very much more densely 

 clothed. The base of nearly all of these setae is surrounded by a group 

 of two to four pores as on the femur, and the anterior face is sup- 

 plied with additional scattered pores. The surface of the tibia is very 

 minutely transversely strigulose in contrast to the femur, which is 

 longitudinally striate. 



The tarsus of the prothoracic leg (fig. 8 F, tar) is rather loosely 

 united to the tibia. The latter bears a rather large terminal membranous 

 area into which the basal segment of the tarsus, the so-called metatarsus, 

 is inserted. There are two rather indefinite condyles on the tarsus, 

 one anterior and one posterior, but no definite corresponding condyles 

 have been observed on the tibia. The tarsus consists of five tarsomeres 

 or tarsites, of which the first four are greatly expanded into trans- 

 verse plates (fig. 8 A, C). The first and second are approximately the 

 same size, the next two decreasing successively in width and length. 

 On the dorsal aspect each of these four tarsomeres is broadly emargi- 

 nate anteriorly, whereas the anterior margin of the ventral side is 

 expanded in a broad curve forming a large flat plate. The space be- 

 tween the dorsal emargination and the ventral plate is membranous 

 and receives the base of the next segment (fig. 8 C). The fifth tarso- 

 mere is elongate, nearly three times as long as wide, and is inserted 

 upon the dorsal side of the preceding tarsomere similarly to the others. 

 It is expanded rather strongly and regularly toward the apex and 

 is rather cylindrical in form. On its distal end the fifth tarsomere bears 

 a pair of claws (fig. 8 B, un) and an expanded membranous lobe carry- 

 ing a small ventral plate, the unguitractor plate (iifr). The claws (fig. 

 8 J) are slightly compressed dorsoventrally, rather strongly curved 

 and tapering, and they articulate with the rounded end of the dorsal 



