176 STUDIES IN THE EVOLUTION OF ANIMALS 



What is there in co^nmon with all these parts ? The reply is, 

 great mobility. If it be true that all mammals descended from 

 armour-plated ancestors, it must be evident that the parts men- 

 tioned were the earliest to get rid of their armour in order that 

 their struggle for existence might be facilitated. If the hands and 

 feet were covered with hard scales, as in the turtle, it is evident 

 they could not be used to run and grasp ; if the eyes were sur- 

 rounded by armour-plates, as in the Ganoid fishes, it is evident that 

 sphincter muscles, to close the eyelids and protect the cornea, could 

 not be developed ; if the base of the ears were not sufficiently 

 mobile to allow of the ear being easily directed towards the source 

 of sound, the muscles that perform that function could not be 

 developed ; so of the lips and vent. All these parts are highly 

 mobile, and must have lost their armour-plating early, in order to 

 admit of that mobility, and hence we see that these parts had 

 ample time to change their coloration long before the body got rid 

 of its carapace, or body-armour. 



A number of animals show a complete or partial circle round 

 the eye, such as the Ocelot of Fig. 19 (a). And also many Cats, 

 such as the Caffre Cat, the Pampas Cat, the Genet, the Binturong, 

 and several others ; ^ and so have some tame Rabbits. Then a 

 number of animals have a spot, emphasised by contrast of colour, 

 over the eye like that of the black and tan dog ; ^ such as the 

 European Lynx, the Caracal, the Clouded Leopard, and others. 

 In many variations of the black and tan Dog, one often meets with 

 individuals which have a complete tan-coloured circle round the 

 eye. 



^ See Royal Natural History, vol. i. 



2 Mr. Worthington G. Smith states that, ' The spots are by no means always tan; a 

 black Dog will sometimes have them white, and a white Dog black. I have a white and 

 tan Fox Terrier in which the spots are very eye-like and jet black ; in a brown Bull-pug 

 of mine the spots are also black.' (See Nature of 15th November 1894.) 



