24 DARWINISM AND HUMAN LIFE 



tiges buried deep below the surface. The whale- 

 bone whale has two sets of teeth which never cut 

 the gum, their place being taken by baleen plates. 

 The New Zealand Kiwi has minute traces of wings, 

 the limbless slow-worm has a rudimentary pectoral 

 girdle, man has scores of vestiges, such as the 

 third eyelid or the ear-moving muscles. Darwin 

 compared these vestiges to the unsounded letters 

 in many words, such as the " o " in leopard, 

 the " b " in doubt, the " g " in reign, which are 

 quite functionless, but tell us something about 

 the history of the words. 



(e) It is a simple but eloquent fact that the 

 geological record in the fossil-bearing rocks shows 

 the gradual appearance of higher and higher 

 forms. At a certain stage in the history of the 

 earth all the animals were Invertebrates ; then 

 fishes appeared, then amphibians, then reptiles, 

 then birds and mammals. As the ages have 

 passed, life has been slowly creeping upwards. 

 The rock-record corresponds in its sequences 

 with those deducible from comparative anatomy 

 and embryology. 



Furthermore, the rock-record reveals quite a 

 number of connecting links, such as Archcvopteryx, 

 the oldest known bird, which has some distinctly 

 reptilian features, and a larger number of generalised 

 types, such as Phenacodus, one of the ancestors 

 of the horse lineage, which bind together several 

 subsequently specialised families, or even orders. 



In certain cases, where fossils have been ob- 

 tained from successive strata, the palaeontological 

 series is wonderfully complete, and the various 

 stages in the evolution of tooth, or limb, or shell 

 appear like the stages in individual development. 



