FIELO-XOTES OX MAMMALS IN TJIE SOUTIIKllN SUJDA^". 343 



sucli a distance cousidei-ing themselves safe from the lions, which 

 follow the great liei'ds eveiywhere, as also from the natives who 

 occasionally hunt the full-grown animals. In the bush, aiirl when 

 in small parties, on the other hand, they appear easier to approach 

 than most game. 



The species doubtless tends to be of larger size and to bear 

 longer horns a-; it trends north : but to divide it into two snl)- 

 races, with a dividing-line about the latitude of Lado, is with- 

 out justification. Although it is unusual to meet with Thiang 

 south of Bor along the river, they of coui-se exist on the great 

 inland plains, which are a continuation of those of the Nuer and 

 Dinka countries, and doubtless the herds make their seasonal 

 mii^ratious south-eastwards towards the Abyssinian and East 

 African borilers, when the winter grazing-grouuds become water- 

 logged. 



During tlie dry season of 1918-19 the Thiang, which had 

 migrated westwards in immense herds, were collected in thou- 

 sands over the Duk and " Toich " country between lats. 7° 15' 

 and 7° 45' in the north of Bor Distiict (E. of Bahr-el-Gebel). 

 A virulent form of dysentery l^roke out among these great herds 

 about the middle of March 1919. This disease, which in its 

 symptoms appeared indistinguishalile from tlie dysentery which 

 affects human beings, was undoubtedly specific in nature and was 

 spread by the droppings of the sick animals fouling the grass. 

 That this was the case was proved by cattle grazing over the 

 same ground becoming affected, while herds kept on clean ground 

 remained healthy. The stomachs of dead animals were usually 

 crammed with food — the hnigs, liver, and heart healthy, but the 

 gall-bladder unnaturally distended. Animals rapidl}'- lost con- 

 dition, but the disease seemed too rapid in its effects to give time 

 for more than a staring coat and a generally pinched appearance. 

 Animals turned away from the herd usually sought the sheltei" 

 of a tree or long grass, stood for a few hours, then lay down, and 

 presentl}^ died. 



The disease was first noticed in the herds grazing in the swampy 

 laaid bordering the river, which had been under water for two 

 yea,rs and was covered with long rich thick grass, but it quickly 

 spread to the other herds which were grazing on the short sweet 

 grass of the Duk coinitr}'- 30 miles inland, and affected them to 

 an extent quite as great as the others. I did not happen to see 

 the remains of any animals except Thiang which had died, 

 although there were large numbers of Roan, Giraffe, Gazelle, 

 Reedbuck, Oribis, and a few Waterbuck and Zebra in the same 

 country. I calculate that perhaps rather more than 10 and less 

 than 15 per cent, of the total Thiang died in about a month. 

 With the arlvent of the rains the big herds broke up, and the 

 dry germs of disease could no longer be distributed by the wind, 

 which probably accounted for the cessation of the sickness. 



T believe that the disease, vvhich I do not consider to have been 

 linderpest, although it closely resembled the latter in some of its 



