DENNIS, ON FOSSIL LIAS. 263 



again you see none of the structure of the kangaroo, but a 

 similarity in the shape of the lacunae and the branching ap- 

 pearance of the canaliculi of the beaver to those of the otter ; 

 and compare both with the same bone of the newt, and though 

 the reptilian character of the latter is apparent, there is a 

 striking similarity in the appearance of the lacunae. Exa- 

 mine a leg-bone of the ring-tailed monkey, and you will find 

 long lacunae more abundant than the oval ; the same will be 

 seen in the bear. These long lacunae are very remarkable in 

 the radius of the chimpanzee, and would seem to be con- 

 nected with suspensive or pulling movements. 



It is a step gained if it is found, upon comparison with the 

 bones of different animals who })ossess in common some 

 faculty, that the structure of their bones indicate it. The 

 next step will be to discover their points of difference as well 

 as their points of agreement with other animals. It may then 

 be possible not only to determine, for instance, whether the 

 animal could spring, but also whether it obtained its prey by 

 a spring, or by bounding escaped from the destroyer. All 

 this implies a thorough knowledge of the microscopic struc- 

 ture of the bones of animals from observations made in diffe- 

 rent parts, and exact comparisons made with the same bones 

 in different animals ; and until this has been done, no satisfac- 

 tory conclusion, in this respect, can be arrived at. If, how- 

 ever, there is any appearance of truth in this opinion, it is for 

 the mathematician to show what effect the difference of shape 

 in the lacunae may have upon the strength and uses of any 

 particular bone. It may be only the sportive fancy of Nature, 

 as she has delighted to besport herself in the varied structure 

 of the foliage of plants ; yet if that sportiveness has only 

 method and arrangement, it may prove of admirable use in 

 distinguishing animals by the microscopic structure of their 

 bones, as plants already have been by that of their leaves. In 

 the fragment of a bone, what clue can we have to the character 

 and habits of the animal to which it once belonged, unless the 

 microscopic structure indicates it. As far as I have been 

 enabled at present to carry my investigations, everything has 

 tended to show that there is a singular correspondence in the 

 microscope structure of animals of similar movements. This 

 matter, indeed, is well worthy of investigation, since if any 

 indication of habits may be deduced from the formal arrange- 

 ment of the lacunae, we shall be able to reconstruct, in some 

 degree, the history of a primeeval aniinal, of which only a 

 fragment of its bone remains. 



The presence or absence of haversian canals are no proof 

 for or against a bone being mammalian, as the radius of one of 



T 2 



