126 J. B. CLELAND. 
Kvidence existed that this same district had been sub- 
jected to a similar visitation years before, inasmuch as the 
settlers who first occupied it, five years before the visita- 
tion mentioned above, found great heaps of the skeletons 
of rats at the bases of old hollow trees, previously occupied 
presumably by owls. 
The sudden and remarkable increase seems rightly attri- 
buted to congenial surroundings and abundant food, 
coupled with the absence of enemies, whilst their disappear- 
ance is capable of explanation by a reversal of these con- 
ditions, aided by their own cannibalism. 
The 1887 Cooper’s Creek and Darling Rat Visitations.— 
The following description is from a commininitenia made 
to me in January, 1916, by Mr. John M. Bagot, and, in its 
nature, it closely. resembles that of Mr. Palmer, though 
floods and abundant herbage were not apparently associ- 
ated with the increase. Doubtless the same, or a closely 
allied, species of rat was responsible. As the species met with 
by Mr. Bennett in the Darling district was identified as 
Epimys rattus (Mus tompson.) presumably the Cooper’s 
Creek rats were the same. Mr. Heber A. Longman, of the 
Queensland Museum, suggests, from the term ‘‘river rats,’’ 
E. norvegicus, but adds that a long snout and rather thin 
body point more to E. rattus. Determinations from de- 
scriptions are, however, as he states, unsatisfactory. 
‘‘In the year 1887 I was witness to an enormous migra- 
tion of rats, thousands of millions, I should say. In that 
year we were building the railway (of which I was one 
of the engineers) round the south shore of Lake Hyre. We 
were camped in tents a mile or two from the dry lake-bed, 
with one or two iron buildings for the protection of stores. 
Suddenly, before precautions could be taken, a plague of 
rats was upon us, and in a very brief space £1000 worth of 
provisions, tents, and other commodities were destroyed. 
