1800.] laktet — rostra aaasn bojtes. 177 



Bi. Delesse, in his letter dated the 19th instant, says : — 

 " The specimen of the rib which I gave you was incontestably 

 found in a sand-pit (sablonUrt I, where it was associated with the 

 bones of animals no longer existing in the country as, for example, 

 (he Beaver. I would observe that the presence of gelatine ran in 

 no way be opposed to the antiquity of that rib. 1 have only just 

 now brought to a conclusion a long series of researches by which 1 

 have shown that bones even of a high antiquity still retain a notable 

 proportion of organic matter. If you take the bones <>t' an Ichthyo- 

 saurus from the Lias, or of reptiles from the Muschelkalk, you will 

 easily satisfy yourself that, in spite of their great antiquity, they still 

 contain a wry ootable proportion of organic matter. Coprolites from 

 the oldest formations contain it. <>n the other hand, hones compa- 

 ratively recent, such, for instance, as those found in caverns or in 

 ailed materials, have no great amount of organic matter. In 

 brief, the preservation of organic matter in bones is very irregular; 

 it depends on the nature of the rock in which they are found at 

 least quite as much as on their antiquity. 



"I pronounce uo opinion as to the nature of the instrument that 

 had been employed in Bawing that rib, for I made no experiments on 

 the subject ; but If. Lartet, whose caution and sagacity are known to 



you, made a special examination of the question along with eminent 



physiologists; and they had no douht that the rib had been cut by 

 a sharp Bint." A. D. 



M. Lartet, in his letter dated the 22nd instant, states as follows: — 



•• I am sorry to learn that a somewhat hasty objection has been 



made to the palasontologica] value of the fragment of bone which you 

 exhibited. I have no right to give any opinion regarding the lo- 

 cality wlere it was found, because I have not visited it ; but the 



opinion of M. DeleSSO, who had an opportunity of examining all its 



geological features, is deserving of all confidence. Among the other 

 fossil remains which he found in that Locality, there is a fragment of 



horn- of a Horse, having also traces of human agency, and which L8 in 



a much more altered condition than thai of the bone he gave you ; 

 but there is another fragment, also bearing the mark of a saw, the 

 appearance of which is quite as fresh as the specimen in your pi 

 sion ; nevertheless, when we endeavoured to authenticate this ; 

 men! specifically, we were unable to d> so by comparing it with the 



homologous part in the skeleton of OUT Living animal.-*. 



•• It i> moreover important to remark that, in any given Locality, 

 all the- hoiio collected do not present the same degree of or) 

 change. That depends, first, on their anatomieal structure being 

 moil' ox Less compact aooording to the species, ami again, chiefly 



on the composition and physical OOnditioO of the mineral matter in 



which they have been in immediate and prolonged ton'. |£r, 

 Eart, in his description of the Hi <■■.■ ~ll ■., (Dublin, 1£ 

 states that a fragment of a rib analysed by l' 31 yielded 12 87 



P-r cent, of animal matter; ami l>r. Apjohn, who analysed another 



