FOSSIL CORALLINES. 39 



unmetamorphosed so that the fossil remains have 

 not been obliterated, Graptolites have been generally 

 found in large numbers. Not unfrequently they are so 

 abundant as to form a kind of carbonaceous matter in 

 the rocks where they are enclosed. Their geographical 

 distribution is exceedingly great, and, as they mark 

 definite geological horizons, no other group of fossils 

 is more valuable in enabling us to arrive at the age 

 of the rock-zones where they are found. 



To the palaeontologist and zoologist the Grapto- 

 lites are unusually interesting, on account of their 

 resemblance to, and yet marked deviation in structure 

 from, a well-known and widely distributed living 

 group of marine objects. Moreover, even among 

 the Graptolites themselves there is a striking dif- 

 ferentiation ; a " differencing," however, which has a 

 foundation of resemblance to start from. Perhaps 

 more papers have been written about the Graptolites 

 than any other fossils, not even excepting Trilobites 

 and Ammonites ; and not a few workers have come to 

 wordy blows about them ! This difference of opinion 

 has arisen from the endeavour to stretch or expand 

 palaeontological facts so as to fit them into the natural 

 history scheme formed for the purpose of classifying 

 and arranging recent animals. Now that the theory 

 of evolution has gained ground among our best 

 naturalists, let us hope its Christian effect will be to 

 remove all accessory causes of " bad blood," by point- 

 ing out that, however perfect our existing scheme of 



