EXTERMINATION IN ANIMAL LIFE. 339 



the animals infected are not speedily killed, or put out of the 

 way, the contagion rapidly spreads, and it is not uncommon for 

 a farmer to lose his entire flock with it. This sad distemper also 

 extends itself to the feres natures. I have shot Hartebeests, 

 Black Wildebeests, Blesbucks, and Springbucks with their bodies 

 covered with the disease. I have known seasons when the three 

 latter animals were so generally affected by it that the vast plains 

 throughout which they are found were covered with hundreds of 

 skulls and skeletons of those that had died therefrom." * At 

 Buenos Ayres, the Coypu (Myiopotamus coypu) was much more 

 abundant some fifty years ago than now, and its skin, which has 

 a fine fur under the long coarse hair, was largely exported to 

 Europe. About that time the Dictator Bosas issued a decree 

 which made the killing of a Coypu a criminal offence. The 

 result was that the animals increased and multiplied exceedingly, 

 and, abandoning their aquatic habits, they became terrestrial and 

 migratory, and swarmed everywhere in search of food. Suddenly 

 a mysterious malady fell on them, from which they quickly 

 perished, and became almost extinct. t Sometimes we can trace 

 the interdependent conditions of these visitations. The liver- 

 fluke of the Sheep {Distomum (Fasciola) hepaticum), as is generally 

 known, is dependent on a small water- snail (Limncea truncatula) 

 as the intermediate host in which its earlier larval, sporocyst, 

 and redia stages are passed through. The wet years 1816, 1817, 

 1830, 1853, and 1854 — memorable for the occurrence of acute 

 liver-rot in England, Germany, and France — showed that the 

 weather also plays a considerable part in extending the suitable 

 ground for Limncea over wide areas, which in dry years may be 

 safe pastures. In 1830 England lost from this cause one and a 

 half million Sheep, representing some four millions of money ; 

 while in 1879-80 three millions died. In 1862 Ireland lost sixty 

 per cent, of the flocks, and in 1882 vast numbers of Sheep 

 perished in Buenos Ayres from this cause, t It is reported that 

 there had been a scarcity of wild animals and birds in Nicaragua 

 since the great hurricane of 1865. § 



* ' Five Years' Hunt. Advent, in S. Africa ' (Compl. Pop. Ed.), p. 74. 

 f Hudson, ' The Naturalist in La Plata,' p. 12. 

 I Of. Gamble, ' Cambridge Nat. Hist.' vol. ii. p. 67. 

 § Collinson, cf. Brown, ' Countries of the World,' vol. hi. p. 38. 



2 D 2 



