CHEUFEE. 155 



cealed ; it usually uncoils in mounting, and is well seen as 

 a very fine hair, protruding from between the valves. 



STENOPTERYX. 



This should be looked for on swallows : you may find 

 them abundantly in nests of the young birds. They run 

 very quickly, but do not attempt to fly, although they have 

 wings, and are good examples of another genus of the Hip- 

 poboscidse. 



Here we find a difference in the male and female ; the 

 former having long narrow wings, ciliated in front, the 

 costal vein more than two thirds the length of the wing, and 

 longitudinal veins crowded close to the costal. The female 

 has short triangular wings ; the rest of the body very like 

 that of Melophagus. 



OENITHOMYIA. 

 (Parasite of Birds.) 



A green and tawny fly, more perfectly winged than the 

 preceding genera, but seldom, if ever, using the wings, and 

 running with great swiftness amongst the feathers of all 

 birds. 



NYCTEEIBIA. 



This is a rare parasite, but quite worth seeking, upon 

 bats. The head is thrown back in an extraordinary manner ; 

 the mouth has a large bulb-like organ, from which proceeds 

 a horny style. It has no wings; the claws are strong, 

 dilated beneath; and the abdomen is terminated by two 

 styles. There are specimens of this in the British Museum. 



CHELIFEE. 



This parasite attacks flies. I have seen a common fly 

 run wildly about the window-pane, shaking itself violently, 

 and apparently in great distress. Upon catching it, I 

 found a small scorpion-like creature fixed upon one of its 

 thighs, by a pair of tremendous claws, hardly could it 

 be detached for examination, and then it ran quickly like a 

 crab, sideways. The Chelifer belongs to the Trachean 



