Mzzsos.—On a Plague of Rats. 201 
great deal of the more remote country in this district, and has moreovor 
great natural aptitude and appetite for observing facts in natural history, 
tells me that he is pretty sure that these rats are the same as he used to 
see in large numbers many years ago round about Tarndale,—the very dis- 
trict that our secretary and his party of explorers visited recently. Here, 
or hereabouts, are the head waters of the Clarence, Awatere, and Wairau. 
Of course it would be absurd for me to pretend to fix the precise spot of the 
original habitat ; but that it was somewhere at the head of the valleys men- 
tioned, or on the western side of Mount Odin, in the Kaikoura Range, seems 
to me indisputable. What other supposition can be entertained ? Consider 
the geography of the locality in question. It is the north-eastern corner of 
the island with the waters of Cook Straits and the Pacific washing its coasts 
on the entire east and north. To these shores trend great mountain chains, 
like the fingers of an enormous stony hand, slightly outstretched from a big 
central mass more in the interior. Between these chains lie the narrow 
valleys mentioned above. The rats first appeared on the shores in the 
north-eastern corner. How did they come there? No one will contend 
that they swam across Cook Straits from the North Island,—or that they 
came from the ocean, or that they journeyed from the middle of the island 
where, as far as we know, they have not even as yet been seen. Unless, 
therefore, we assume that they dropped from the skies, or form an illustra- 
tion, like Van Helmont’s mice, of the doctrine of abiogenesis, we are driven 
to the conclusion that their original habitat was somewhere in the high, 
rough, and secluded country on the western side of the Kaikoura Range, 
whence they descended by one of the narrow valleys that I have referred to. 
They probably were driven out of their old haunts by the struggle for exist- 
ence (or subsistence, if you prefer the word), even as in many cases human 
beings are driven to emigrate ; and, if we enquire what it was that pressed 
so severely upon the rodents, we shall probably agree that the best explana- 
tion of the movement en masse is in some exceptional climatic condition. 
Let it be borne in mind that last summer was very wet, and last winter 
very cold, the amount of snow lying on the high lands in the interior having 
been reported from time to time to be exceptionally large. In the month of 
_ September 5,000 sheep were at one station alone, in the Kaikoura District, 
Kekerangu, lost through heavy snow. Under pressure of famine, therefore, 
the rats, though contented enough with their habitat under ordinary circum- 
stances, naturally braved new dangers, and made their way to the more "S a 
fertile and cultivated lower country in the valleys and along the coast, e 
where food would be found more abundantly. Another supposition would a 
be that the struggle for existence arises from excessive increase in numbers, 
rather than hard winters; and a third, that the animals are attracted by 
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