166 



laying eggs or producing a number of small living larvae, which 

 lead a free and active existence, feeding until full-grown, the 

 female Hippoboscid, as already stated, produces at intervals a 

 single adult larva, which, as in Glossina, is retained within the 

 oviduct of the mother and nourished until maturity by means 

 of the secretion of a pair of greatly ramified glands. But while, 

 except for the " black hood " at the posterior extremity, the 

 Tsetse-fly larva on being deposited looks like an ordinary 

 maggot, shows distinct segmentation, and is capable of crawling 

 actively away to seek a hiding-place in which to pupate, the 

 Hippoboscid larva on extrusion is a sac-like, ovoid or flattened 

 globular body, which exhibits little or no trace of segmentation, and is 

 entirely incapable of movement. On being deposited, a larva 

 belonging to the present family is whitish or yellowish in colour, 

 with (except in Melophagus) a conspicuous black area or cap 

 (divided into six radial tubercles with intervening furrows in the 

 genus Ornithomyia) at the posterior pole, and a small depression 

 or papilla at the opposite one marking the position of the mouth. 

 In the centre of the black cap (which is obviously reminiscent of the 

 " black hood " of the larva of Glossina) are situate the posterior 

 stigmata or respiratory apertures (in a deep pit in the larva of 

 Ornithomyia), while on the ventral surface in the middle line, just 

 in front of the black cap, is seen the small circular anus. Within 

 a very short time after extrusion the larva becomes converted into 

 a pupa without any modification in form, the change being indicated 

 by the chitinisation and darkening of the larval skin to constitute 

 the puparium or pupal envelope ; by this alteration in colour the 

 contrast between the black cap and the remainder of the integument 

 becomes obliterated. The perfect insect subsequently makes its 

 escape by splitting off a cap from the anterior pole of the puparium, 

 after the manner of the Muscidae. 



There is at present nothing to connect any species 



Hippoboscidae of Hippoboscidae with disease among human 



and Disease, beings, and from the mode of life of these flies 



it is <i priori improbable that they will ever prove 

 to be disseminators of micro-organisms pathogenic to man. On 



