202 Transactions. — Zoology. 



some particular species of food which, in this particular 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 attracting 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 augustce 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 

 botb the European species — Mus rattits and Mus decumanus — 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 ivhat is this rat ? Is it a complete stranger or an old acquaint^ 

 ance ? Here is a full and particular description of the adult male. 



