EVIDENCES OF EVOLUTION 45 



were any mammals; similarly, the Eusta- 

 chian tube which runs past the ear to the 

 back of the mouth in amphibians, reptiles, 

 birds and mammals corresponds to the first 

 gill-cleft or spiracle of a shark. Begging 

 the question, we may state it as one of the 

 laws of evolution that markedly new st.mr- 



r arisen 



mation^pf old structures of quite different*/ 



CLASSIFICATION. Some reckon that therg 

 e ovef g, million (lifteroiil: specie^ of Jiying- 

 creatures, and, in any case, there are many 

 myriads. Now these species are, in many 

 cases, linked together by varifitfi es which 

 make strict ^evftra.p^fi Difficult. They are 

 like constellations, well-defined at first glance, 

 which on closer inspection are seen to be 

 connected by outlying members with ad- 

 jacent constellations. Moreover, ijiey can 

 be rationally arranged in genera, orders, 

 families . ... and classes ; yet betweeiL_ihse 

 there appear not a few remarkably connect- 

 ingjjnl^s; there is structural progress from 

 the unicellular organisms upwards along 

 various lines of organization; and it is 

 possible to make a provisional genealogical 



^ 11 ' ^ 1 T ' s 



though the mutual . jvglajj.Qnfi Q f 

 Ithe^arger branches are, still very 



