156 DE. J. KIBK OK THE TSETSE ELY OE TBOPICAL AEEICA. 



base expanded into a large horny body of cordate form. The 

 upper surface of this proboscis is grooved nearly to its distal ex- 

 tremity, and contains a slender glassy style, equal to the groove 

 in length, which may be raised from its protecting sheath. This 

 style is the biting instrument ; it is convex above, deeply concave 

 beneath, and cut off obliquely at the point; the margins are 

 slightly waved, and near the base furnished with a series of mi- 

 nute pedunculate hairs. Where it joins the proboscis, near the 

 base of the lobed dilated swelling, the edges approximate and 

 form a tube. 



In the description of Glossina longipalpis, "Wied., given by 

 Mocquart, it is suggested that within the grooved style there pro- 

 bably exists a tongue or second part. This Professor Westwood 

 has figured, which in fact has no existence in the " Tsetse." 



It has been suggested that the horny dilatation at the base of 

 the proboscis may contain some very strong poison, or a gland 

 for its secretion ; on dissection I find in it nothing but a series 

 of large muscular bundles arising from a common tendon at- 

 tached to the grooved body of the proboscis, some of the muscular 

 bundles embracing and attached at the other end to the mem- 

 branous oesophagus or continuation of the grooved style. 



"When in the act of biting, the insect throws forward the two 

 hairy palpi and raises the grooved style from the upper surface of 

 the proboscis, .which at the same time is turned backwards ; 

 then, by forcing the head down on the animal, the style is in- 

 serted, — no doubt in this assisted by the powerful muscular 

 arrangement at its base. 



The irritation which follows the bite in man shows that some 

 irritant matter is at the same time injected (although no organ 

 for its secretion has yet been detected), the object of which is no 

 doubt to cause a local congestion, and thus facilitate the sucking 

 of blood. The accidental effects of this, which in animals among 

 whom the "Tsetse" naturally lives produces no after result, in 

 the domestic animals before- named proves fatal. 



