202 Objects for the Microscope. 



there is an infinite variety of structure adapted to the 

 necessities of the animal, more or less of strength, or of 

 lightness, or of flexibility. 



A knowledge of this has enabled Owen, the great osteo- 

 logist, to ascertain the order and exact position of an ante- 

 diluvian reptile from a mere fragment of fossil bone. 



By microscopic examination of bone the existence of 

 Keaper reptiles in old red sandstone has been determined, 

 and the supposed reptile Saurocephalus been removed into 

 the class of fishes. It is marvellous to observe in the 

 section of a fossil bone which belonged to an animal of 

 extinct race, such as the huge Mastodon and Megatherium, 

 the very same structure and proportionate size of bone-cells 

 that we find in our domestic animals, and in man himself; 

 to compare a section of bone from the colossal Iguanodon 

 with one from the timid lizard, and find them modelled after 

 the same type, and by the peculiar form and large size of 

 the lacunaB and canaliculi to recognise the reptile ; or to 

 examine a section from the fossil bones of the gigantic 

 Dinornis, whose species has been extinct for ages, and yet 

 find in the still existing Apteryx a continuance of the race, 

 and the unmistakable small lacunae of Birds. 



It was from a fossil bone of the Dinornis and micro- 

 scopical examination that Professor Owen ascertained that 

 it was the femur or thigh-bone of a Bird that the bird 

 was large, heavy, sluggish of the ostrich tribe, and there- 

 fore probably with the habits of that bird. Afterwards, 

 when a few more bones were sent to the naturalist, he not 

 only discovered that they belonged to nine different species, 

 but was able to determine that one Dinornis was a bird ten 

 feet six inches high, another nine feet, another five feet, and 

 so on. 



With a very moderate knowledge of the structure of 

 bone, and a habit of observation and comparison, the student 

 of geology or of natural history may be able to ascertain 

 to which class of vertebrate animals any bone, fossil or 

 recent, belongs. A collection of the jaws and small bones 

 of Moles, Rabbits, Weasels, and Rats, will give beautiful 

 preparations. Nor are they difficult to mount ; all we require 



