LOSS OF CALCAREOUS ARMOUR IN MAMMALS 211 



cranial brain, and in some cases, as in the Stegosanrus, there is 

 reason to believe that an additional lumbar brain existed, as a part 

 of the spinal cord. 



I think I have said enough to indicate by what possible causes 

 the plate-armour of ancient animals may have been got rid of, and 

 therefore shall not follow up this speculation any further. 



The upshot has been that the ancestors of the Jaguar and Leo- 

 pard, from a similar lime-famine, lost their calcareous carapace, 

 which consisted of 0#-rOsettes, and so their descendants have 

 had to be satisfied, with profit to themselves, with rosette stamps 

 instead ! 



I believe that all mammals, including marsupials, descended 

 from armoured ancestors, and that a famine of lime by degrees 

 relieved them of the calcareous armour, but left on their skins the 

 stamp of the armour-plates, and, in some cases, that of the carapace 

 as a whole. By slow degrees these also became modified in various 

 ways, and even wholly obliterated. The least altered from the 

 originals, after the armour wholly disappeared, is the Jaguar skin ; 

 then the others follow somewhat in this order: Leopards slightly 

 altered ; spotted and dappled mammals of all degrees and kinds ; 

 more or less altered striped mammals ; piebald mammals ; mammals 

 with self-coloured bodies, but with ringed tails ; and lastly, mammals 

 self-coloured all over. 



