POSTSCRIPT 133 



have been so stamped in the nerve-centres that even time has not 

 succeeded in wholly defacing them ! 



It is a marvel to me also that marsupials, being the oldest mammals, 

 have a7iything left on their exterior to give any indication of their descent 

 from, as I think, the common stock of armoured mammals ! 



Of this there cannot be much doubt. Armoured vertebrates — Fishes, 

 Saurians, Chelonians, Glyptodonts, etc., formed, at one time of the earth's 

 history, a vast portion of its inhabitants. 



In the Royal Natural History, vol. iii. p. 64, indication is given of 

 the existence in former times of some sort of armoured Dolphins. Under 

 extinct Cetacean-like animals — Zeuglodonts, it says, ' So far as they can be 

 determined, the general characters of these Zeuglodonts are such as we 

 should expect to find in an ancestral group of Cetaceans ; but it is 

 remarkable that the body appears to have been protected by an armour of 

 bony plates.' (!) 



