( o3G ) 



bristles in the male. (PI. XVa. f. 3), while in the female there arc two on each side. 

 In the case of 7'. spectabilia again the inale has three and the female five bristles on 

 each side in this position. The nnmber of the bristles on the sternites is from 

 two to six. Here again the nnmbers vary in the sexes. 



While the third, fourth, fiftl),and sixtli sternites are covered by their respective 

 tergites, the reverse is the case in botli sexes with regard to the second segment. 

 In this case the steruite covers the lower portion of the tergite (Pi. XVa. XVI. f. 1. 

 3. 4. 6. 7. 11). The seventh segment of the viale, like the preceding five segments, 

 has its tergite covered by its sternite, and is normal in structure. In T. agtjrtes 

 and otlier members of the same genus the seventh sternite of the fe mole exhibits 

 some peculiar characters. In this case the sternite covers the tergite, while in the 

 mule, as I have previously mentioned, the tergite covers the sternite. This seventh 

 sternite is narrower mesially than at the sides. The dilated lateral portion is 

 deeply sinuate, thus consisting of an upper broad and a lower narrow lobe (PI. XVa. 

 f. '£). In Typldopsylla pentacanthiis and T. dasycnemus the lobes are also present 

 (PI. XVa. f. .")) ; they differ, however, in shape in each species. In the genus 

 Ceratopsyllu (PI. XVI. f. 0. 7) the seventh sternite is still more enlarged, but its 

 outer edge is not sinuate. 



The eighth segment of the fenuile of at/i/rtes diti'ers entirely from the other 

 segments. The sternite is reduced to two narrow bottle-shaped pieces, which bear 

 a few short hairs at the toj) (PI. XVII. f 24. viii. v). The sternite th(yrefore is 

 mesially divided, which is not the case witli segments 2 to 7. In a lateral 

 view tlie sternite would be hardly noticed (PI. XVa. f 2. viii. v). The se[iaration 

 of the sternite into two halves does not seem to be complete in all fleas ; in Pide.r 

 (joniocepkahis, for instance, the two narrow plates remain united at the base. 



The eighth tergite is correspondingly enlarged, forming a complete ring, tlie 

 ventral edges of wliicli nearly toncli eacli other : in fact they almost conceal the 

 steruite from view. The upjier portion of the tergite is narrower than the lower part. 

 It is divided, moreover, in the middle, the division nearly reaching the l)ase. This 

 peculiarity is well shown in PI. XVII. f. 2.5, which represents the dorsal view of 

 the eightli segment. In tlie figure the two stigmata, which lie close to the middle 

 sinus, are also represented. These, taken witli the trachea, are haninier-shajied in 

 apjiearance. Their mouths are densely clothed with fine hairs. The bristles near 

 the ventral edges of the eighth tergite, shown in PI. XVII. f. 24 and 25, arc 

 generally quite constant in length, number, and position. The difference in the 

 mesial jiortion of tlie eighth tergite of the two sexes of T. af/i/rteg is very con- 

 si)icnous (PL XVII. f 14. viii. d, and f. 25. viii. d). 



The portion following the eighth segment corresponds to the ninth and tentli 

 segments in the imile, of which mention is made further on. The structure, 

 however, of this jiortion of the abdomen in the female is dift'erout from the structure 

 of the end of the abdomen in the male. In fact I am not yet jirepared to give a 

 decided opinion on the homology of these portions of the morphology oi the fe mule. 

 In the view from above, PI. XVII. f. 17, a plate (a) is represented on each side, 

 the two ])lates Iieing su])arate in the middle line. In addition to this a larger 

 undivided plate (lij is shown, in tlie middle of which the ovate sensual plate is 

 placed. Finally the two jialpi-like jirocesses (c) are shown. In a lateral view, 

 PI. XVII. f. 18, the same plates are represented. In addition to these, however, 

 two more plates are present, marked in the figure a' and b'. The plate marked 

 a' is ventral to the ]»late marked a : and the ])late b' is likewise ventral to b. 



