88 MEDICAL ENTOMOLOGY 



parts : superior and inferior claspers, the editum, harpes, juxta, penis, 

 a median process and a connecting membrane. The superior claspers 

 are the largest and most important parts of the apparatus ; they are 

 stout hook-shaped organs, terminating in blunt chitinous points, which in 

 many species are bifid. They are attached by their stout bases to 

 that portion of the basal plate which is anterior when the hypopygium 

 is closed and posterior when it is open, and are also capable of a 

 limited amount of movement on their own attachments. The editum 

 is a flange-like expansion, arising from the basal plate about the 

 middle of its length on each side, external to the superior claspers. 

 It bears a tuft of hairs. The inferior claspers are smaller than the 

 superior, and are attached to the basal plate between them near 

 the articulation with the eighth segment ; they are softer, and do not 

 terminate in chitinous points, but bear numerous fine and long hairs. 

 Newstead attaches great importance to these organs, which appear 

 to vary a great deal in the different groups of species. The harpes 

 are bilateral organs situated between the attached bases of the superior 

 claspers, and are most conspicuous in the fusca group. They may be 

 armed with small chitinous hook-shaped sclerites near the terminal 

 end. The juxta or penis sheath is a median structure extending from 

 the apices of the inferior claspers to the level of the bases of the superior 

 ones ; it is tubular, divided and expanded at its distal end, and is, 

 with the penis, everted along with the harpes. It has on each side 

 a membraneous expansion, the vesica, supported by the harpes. The 

 median process, when present, lies between the inferior claspers in 

 the middle line, and is highly chitinized. The connecting membrane, 

 present only in the palpalis and morsitans group, stretches between 

 the superior claspers. 



The modifications of this highly complex apparatus will be dealt 

 with in a later chapter, in connection with the species for the differentia- 

 tion of which the characters which it provides are used. The structures 

 in Glossina, elaborate as they are, are not more so than in other 

 groups, and the great difficulty in determining the relationships and 

 homology of the parts must necessarily militate against their general 

 use, for the present at least, in systematic Dipterology. 



The external genital apparatus of the female is generally much 

 simpler than that of the male, and consists of a tube which can, to 



a greater or less extent, be protruded from the abdo- 

 External Genitalia 



of the Female men anc * a g am closed up like a telescope. It is 

 only developed to a high degree in those forms in 



