THE JUMPING PLANT-LICE OR PSYLLIDiE OE THE NEW WORLD. 15 



Legs. — The coxae are large and subglobose or ovoid, the metacoxas 

 being very much larger and more complicated in their structure 

 (see discussion of the metapleurse above). The fore- and metacoxse 

 are usually contiguous, while the middle pair are not. 



The trochanter is freely movable in the acetabulum of the coxa. 

 The femur is long and large, and the hind pair are weU supphed with 

 muscles for springing. The tibia is as long as or longer than the 

 femm* and relatively slender. In many genera there is a spur at 

 the base, and in all the genera there are from three to many black 

 spines at the apex. 



The tarsi are two-segmented. The apical segment bears two large 

 sharp claws with a long seta between them. The basal segment in 

 most genera, except Triozinse, bears two large claw-like spines at 

 the apex, one extending out on each side of the distal segment. 



ABDOMEN. 

 Figs. 1, 8, 13-14. 



The number of segments in the abdomen is reduced below the 

 number in the typical or generalized insect. There are five easily 

 visible segments besides the genital segment in the female and six 

 plus the genital segment in the male. In addition to this there are 

 several segments reduced or suppressed and several represented by 

 the gonapophyses in both sexes. The total number has been said 

 by Witlaczil and others to be ten, while Heymons ^ shows eleven to be 

 the total number in the several genera of Homoptera, though Psyl- 

 idse are not expUcitly included. I find that the latter, eleven, is 

 correct. 



The first segment has been said to be fused with the metathorax 

 as a propodium. This is not possible according to the position of 

 the first spiracle. Stough ('10:151) states that there are seven spira- 

 cles on the abdomen. In Psylla pyricola (figs. 13, 14) and in aU of 

 the other species which I have examined there are eight in both 

 sexes. Two are between the metathorax and first tergite. The 

 latter is much reduced and is not the first of the large tergites. There 

 are two very small chitinized sclerites below these and before the 

 first large urite. It is obvious that these are two atrophied urites 

 and represent two suppressed abdominal segments. The tergites 

 of the first two seem to be wanting entirely, while that of the third 

 is present as a reduced sclerite. The fourth to eighth tergites, inclu- 

 sive, are distinct enough. The ninth segment in the female is 

 represented by the ventral valve of the genital segment. The tenth 

 is represented by the ovipositor sheath within the genital segment 

 and the eleventh segment by the dorsal or anal valve of the same 

 genital segment. The eighth urite is suppressed. In the male the 

 segments are similar up to the ninth. The ninth tergite is suppressed 



1 Heymons, R. Beitrage zur Morphologie und Entwickelunggeschichte der Rhynchoten, 1899. 



