:$70 



pubescence but an the middle part of each segment and on mostly 

 part of the fourth and fifth segments with black one, the seventh 

 segment clothed with dense longer black bristly hairs especially about 

 the middle. 



Length: 23-25 mm. 



This species is closely allied to Tabanus yao. Macquart, but 

 distinguished from it in the female, by the blackish femora, tarsi and 

 abdomen, by the black pubescence on the frontal stripe, and by many 

 other minor points. Although it may be a Japanese subform of T. 

 yao as pointed out by Miss Ricardo, the name trigonus may remain 

 safely as a specific one until many of the specimens of yao are careful- 

 ly studied. 



T. trigonus varies but very little in the colour of the abdomen 

 and of the legs, as well as in the amount of the blackish pubescence 

 as already described above. 



This large fly is rather common in Japan, but the occurence 

 is quite restricted to the main Island of Japan, Shikoku, and Kiushu, 

 while in Hokkaido and others it does not occur, as I have records 

 only from Akita, Tokio, Hakone, Tateyama, Izu, Gifu, Matsuyama, 

 Kioto, Kumamoto, Oita, Hitoyoshi, Miyazaki, and Oshima (Izu), from 

 June 1 2th, to September 9th. 



The females are well known cattle or horse biters, and they 

 sometimes pierce through the skin, of the back of our body with their 

 large proboscis. Their bites are rather painful, and the effects almost 

 always last three or four days. The female flies are most abundant in 

 August throughout the countries where they occur, especially from about 

 2 to 7 o'clock in the afternoon. It is believed by many of our verterinary 

 surgeon that this species may be a good transmitter of a certain infec- 

 tious anoemia of horses. The males are rather uncommon, hut we 

 could take some specimens with care among bushes, and they sometimes 

 dence in hot sunshine between eleven and twelve o'clock., in groups of, 

 from two to four individuals above various bushes. 



