820 



THE DIPTERA 



Other Genera. 



In 1906 Griinberg described three genera, with one species in each, as 

 belonging to the Tabaninae — viz., Thaumastocera- — T. akwa — in West Africa; 

 Holocevia — H. nohilis — in Tropical East Africa ; Parhcsmatopota — P. cognata — 

 in Tropical East Africa and Zanzibar; while other genera are Hexatoma Meigen 

 in Europe, Dasyhasis Macquart in South America and Australia, Bolhodimyia 

 Bigot in South America, Udenocera Ricardo in Ceylon, Diachlorus Osten 

 Sacken in America, Stibasoma Schiner in South America, Acanthocem Mac- 

 quart in South America, DichelaceraMa-cquait in South America, and Selasoma 

 Macquart in South America. 



Pangoniin^. 



Tabanidae with hind tibias armed at the tips with spurs. 



I. Prosboscis short. 



1. Antennae longer than the head — Chrysops. 



2. Antennae shorter than the head — Silvins. 

 11. Proboscis long. 



1. Proboscis little longer than the head — Cadicera. 



2. Proboscis usually much longer than the head, often 



longer than the body — Pangonia. 



Chrysops Meigen, 1803. 



This genus has become of greater importance since Leiper has 

 shown that it includes the carrier of Loa loa Cobbold, 1864, which 

 in its turn is suspected to be the cause of Calabar swellings. 



The genus is world-wide in its distribution, and is said to contain 

 more than 160 species, of which some seventeen or more have been 



Fig. 413. — Chrysops wellmani Austen: Female. (X4i-) 



found in the Ethiopian region. The African flies belonging to the 

 genus are of medium size, not exceeding 10-5 millimetres in length 

 according to Austen. The wings of the majority show a conspicuous 

 black band (Fig. 413) running across the surface. There are three 

 ocelli on the crown of the head. The characters of the antennae are 

 shown in Fig. 408, h, h' ; in the latter the first joint is shown to be 

 conspicuously swollen. During life the eyes are of a golden-green 



