12 ROBERT NEWSTEAD — A REVISIOM OF THE TSETSE-FLIES (GLOSSINA), 



Their chief fimction is apparently to grip the abdomen of the female, and in 

 several examples of G. morsitans and G. submorsitans, the distal margins present 

 a distinctly chipped or worn appearance ; whether this is produced by the act of 

 coition or otherwise is uncertain. These organs are furnished with nunaerous 

 slender bristles some of which are of great length, more especially so in 

 G. longqyalpis. 



2. Editum (e in all the ligures). This is a Hange-like extension of the body- 

 wall and is invariably furnished with a number of bristles, some of which are of 

 great length and may extend to the middle area of the superior claspers 

 {see fig. 14, p. 29). 



3. Inferior claspers (ic in all the figures). These are very important organs, 

 as they afford, in many instances, very striking morphological differences, by 

 which closely allied species may be determined. They are very large in the 

 fiisca group ; and in the palpuUs group they are deeply folded at their bases, 

 and the distal extremities are curiously modified. In the morsitans group they 

 are not very clearly defined and their true structure has not yet been adequately 

 determined, owing to the complicated folds which they present ; for this reason 

 also they are not shown in the illustrations. U'he function of these organs is at 

 present unknown ; but it should be a comparatively easy matter to find out in 

 specimens preserved in coitu. 



4. Harpes (h in all the figures). These organs are bilateral, and are most 

 highly developed in the fusca group, more especially so in G. fusca. In the 

 remaining groups these appendages are more or less rudimentary and very 

 similar in form. 



5. Juxta or penis sheath (j in all the figures). In all of the species included 

 in groups II and III this is more or less tubular in form, with the distal portion 

 strongly dilated and more or less deeply divided. 



6. The penis (/>) which lies in the middle of the sheath is a slender tube-like 

 organ dilated distally, the extremity, in some instances ( G. longipalpis, etc.) 

 bearing four or five minute perforations. The vesica {v in all the figures) is a 

 thin membranous extension of the juxta, supported, apparently, by the harpes. 

 In G.fnsca, G. niyrofusca and G. brcvipalpis, li forms a complete tube presenting 

 many irregular longitudinal folds and in some cases {G. niijrofusca) regular 

 transverse ones also. In the species included in groups II and III it is quite 

 rudimentary and in some species it resembles the harpes both in form and size, so 

 far at least as one can judge by viewing it in optical section. 



7. Median process {mp in all the figures). This organ has been foiuid only in 

 t\\<i fusca group. It lies in the position in which one would expect to find the 

 anus ; but it appears to be a non-tubular process and it is so highly chitinised in 

 G. brevipalpis as to resist the action of stains. It lies in the middle line between 

 the inferior claspers, and is sligiitly dilated distally and deeply grooved medially 

 along its upper edge. 



8. Connecting meinbruae (cm in all the figures). This is present in the palpalis 

 and morsitans groups, but is absent in the fusca grouj). It is in all cases finely 

 spinose and, when at rest (fig. 2), lies folded on either side of the median line. 



