292 MEDICAL ENTOMOLOGY 



separating the species from one another, they should be noted in the 

 fresh condition and recorded. As a rule the eyes of the males have no 

 bands on the dorsal 'portion, but are marked like those of the female 

 in th,e lower area where the facets are smaller. 



The flies of this genus are widely distributed, and many of the species 

 are common where they occur. Haematopota pluvialis, L., which is 

 figured on Plate XLI, is perhaps the commonest European species. A 

 large -number are found in the tropics, Africa being notably rich in species. 

 According to Neave the African species are more abundant in higher 

 localities; they have been found at an altitude of 10,000 feet. Neave 

 points out in a recent paper that the East African species are somewhat 

 irregularly distributed, being abundant in some parts and rare in others, 

 and that the season in which they are prevalent is very short. He 

 shows that the lighter species are found mainly in open short grass 

 country, while the darker ones are confined to well-wooded localities in 

 the vicinity of streams. 



GENUS SILVIUS, MEIGEN 



Medium-sized flies with clear hyaline wings. Antennae short, the 

 second joint much shorter than the first ; the third segment has a well 

 developed dorsal tooth at its basal end, and consists of four segments. 

 The eyes are uniformly coloured and the facets are all of one size in 

 both sexes. 



The species of this genus are widely distributed. The females are 

 blood-suckers, but are not aggressive unless their haunts are approached. 

 Neave states that the female of S. fallax, Austen, frequents water holes 

 and attacks the natives as they go to draw water. 



GENUS CADICERA, MACQUART 



Large robust flies with dark wings. The head is flattened antero- 

 posteriorly. The abdomen is broadened laterally, and is generally 

 brightly coloured. Antennae three- jointed, simple, and without a spur ; 

 the distal joint has seven cumulations. The proboscis is as a rule longer 

 than the head. 



Most of the species of this genus are confined to South Africa, but 

 some have been recorded from other parts of the same continent. One 

 species is known from Nyasaland, and another, C. speciosus, Austen, 

 has been found by Neave in German East Africa ; the latter was taken 

 in wooded country at the foot of Mount Kifulufulu, and was seen to bite 

 cattle. 



