12 ROBERT NEWSTEAD—A REVISION OF THE TSETSE-FLIES (GLOSSINA), 
Their chief function 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 numerous 
slender bristles some of which are of great length, more especially so in 
G. longipalpis. 
2. Editum (e in all the figures). This is a flange-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 
fusca group; and in the palpalis group they are deeply folded at their bases, 
and the distal extremities are curiously modified. In the mors?tans 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. The 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. Juvta or penis sheath (j in all the figures). In all of the species included 
in groups II and IIT this is more or less tubular in form, with the distal portion 
strongly dilated and more or less deeply divided. 
6. The penis (p) 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. fusca, G. nigrofusca and G, brevipalpis, it forms a complete tube presenting 
many irregular longitudinal folds and in some cases (G. nigrofusca) 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 found only in 
the fusea 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 liae between 
the inferior claspers, and is slightly dilated distally and deeply grooved medially 
along its upper edge. 
8. Connecting membrane (cm in all the figures). This is present in the palpalis 
and morsitans groups, but is absent in the /usca group. It is in all cases finely 
spinose and, when at rest (fig. 2), lies folded on either side of the median line, 
