202 STUDIES IN THE EVOLUTION OF ANIMALS 



ventral surface, as the part least needing armour, especially in land 

 animals, and a type of mammal was reached which is now 

 represented by the surviving Armadillos and Pangolins. 



When the armour disappeared from the ventral surface it left 

 behind the imprints of armour-rosettes in the shape of pigment- 

 rosettes and spots. 



Later on, for some reason which I shall come to in a little 

 while, a type of animal was reached in which the dorsal armour 

 also began to dwindle. For instance, Thoracophorus and Mylodon 

 Darwinii had separate scutes or plates on their carapace, and 

 others, such as Cariodenna, had only vestiges of plates. 



We see a similar diminution and scattering of dermal plates, 

 and probably from the same cause, in some Trygons and in 

 Echinorhinus spinosus among fishes. 



This dermal rachitis was evidently progressive, and eventually 

 a stage was reached in which the whole armour disappeared, 

 leaving only imprints of its former bone-rosettes. 



Thus we come to the armourless ancestral forms of the modern 

 Jaguar and Leopards, with only pictures of scutes, with all their 

 modifications, as detailed in the foregoing pages. 



; Of course all this descent is a speculation, but it is founded on 

 the facts which I have endeavoured to place before the reader. , I 

 need not add that all these changes did not occur in a day. 



There are many minute and other forms of spotting and 

 striping among different classes of animals which cannot honestly 

 be said to be of any use whatever for individual protection, 

 although they may be of service for social ends, such as recognition, 

 etc. Animals, whose minds are not so much engrossed by fashions 

 and the frivolities of society, may perhaps take far more notice of 

 a few characteristic spots and stripes on their associates than my 

 friend the Lady- Fellow of the Zoological Society could do, who, 



