6 A necdotal Natural History. 



Our Australian colonists talk and write with mar- 

 vellous composure of wolves, bears, monkeys, bats, 

 cats, squirrels, rats, and mice as inhabiting the country. 

 Similarly, American writers sadly bewilder the tyro in 

 zoology by mentioning American buffaloes, lions, 

 tigers, and panthers, all these creatures being strictly 

 confined to the old world. The ' Robin ' again, so 

 often mentioned in American literature, is not our 

 English redbreast, as is usually assumed, but an 

 erroneous name for the migratory thrush, a bird far 

 larger than the redbreast and belonging to a totally 

 different group. 



The squirrels belong to the great division of the 

 rodents, which comprise nearly a third of all the known 

 mammalia. The animals of this group are distin- 

 guished by the possession of two powerful chisel-edged 

 incisor teeth in each jaw, formed for cutting or 

 gnawing away hard substances, and which are replaced 

 by fresh material as fast as they are worn away. The 

 power of these incisor teeth is strikingly exemplified 

 in the beaver, which has been known to gnaw its 

 way through logs no less than eighteen inches in 

 diameter. 



Were there not some means of replacing these 

 teeth as quickly as they are worn down, the death of 

 the animals would speedily follow, as they would 

 shortly starve from their inability to procure food. 

 In order to avoid this, the teeth are continually forced 

 forward from the jaw by the formation of fresh sub- 

 stance at the base, which is secreted by a pulpy sub- 

 stance at the root of the tooth. Now, as this growth 

 takes place whether the teeth are used or not, it 

 follows that, unless they were in constant use, they 

 would soon increase to an inordinate length, and 

 before very long would project from the mouth. Such 

 an event does occasionally occur, when by some 



