209 Transactions. —Zoology. E 
some partieular species of food which, in this partieular year, and at this 
particular season, their instinct or their keen sense tells them would be 
found hereabouts in abundance.. In connection with this supposition, I 
have heard it suggested that, as this year the birch-trees have been seeding 
abundantly, and thus attraeting the kakas, so perhaps the rats have been 
drawn down from their remote homes by the same seductive food. I 
incline to the opinion that the recent hard winter has procured this visita- 
tion for us. 
A curious fact, if it be one, here comes in. I have examined many 
of these animals, and have not found a single female. One of my neigh- 
bours has examined two hundred of them; and a Maori, at the pa 
beyond Wakapuaka, one hundred, with the same negative result. I have 
not heard of many female specimens as yet being taken amongst the whole 
host. Some females have, however, been taken; and in one case, at 
Wakapuaka, they were found breeding. If it really be the case that 
nearly all these visitors of ours are males, we may safely prognosticate that, 
unless there be a fusion of this race with that of the Mus decumanus or 
Norwegian rat, which we have with us (a thing most unlikely to occur), the 
infliction under which we suffer will not be of long continuance. Arguing 
by analogy, we should say that the young males driven, or volunteering, on 
a dangerous foray, will not stay long from their old quarters if they be un- 
accompanied by the other sex. But is it possible that the weaker males 
have been driven out by the stronger through jealousy,—or that, through 
res augusta domi, like drones from a hive of bees, they have decamped to 
escape the massacre with which they were threatened by a combination of 
the strongest males, and the whole body of females? It will not be safe to 
raise a theoretical superstructure as yet upon the evidence produced. More 
observation is wanted, so that we may have a foundation of fact, and then 
we may try to answer the above questions. 
Invasions of rats, from whatever cause produced, are not by any means 
rare in the annals of natural history. They have occurred, I am told, from 
time to time in different parts of this colony; and it is quite certain that 
both the European species—Mus rattus and Mus decwmanus—appeared in 
Europe quite suddenly in comparatively modern times—the black rat about 
the year 1500, and the brown one, stupidly called the Norwegian rat, about 
the year 1727; both came from Central Asia, and must therefore have 
travelled much further than our present troublesome little visitors here in 
Nelson; that is, if our supposition as to the whereabouts of their original 
home be accepted. 
2. But what is this rat? Is it a complete stranger or an old acquaint- 
ance? Here is a full and particular description of the adult male. 
