RECENT ADDITIONS TO ANCIENT SEDIMENTS. 367 



the working palaeontologist. We are probably on the 

 threshold of great discoveries in this department of the 

 science, and it is easy to see the methods of work which 

 will be pursued in the immediate future. A fuller examina- 

 tion of such diverse deposits of similar age as those of 

 Moffat and Girvan will doubtless throw much light on the 

 influence of sediment and climatic conditions on the distri- 

 bution, migration, variation and extinction of organisms. 

 But it is in the study of phylogenesis that we may expect 

 the most important results : a suggestion as to the 

 methods of research to be pursued in this study is given by 

 Hermann in his inaugural dissertation (37), as far as the 

 graptolites are concerned. We now possess material for 

 the formation of a fairly complete phylogenetic tree for 

 the graptolites, and their biographer will undoubtedly be 

 able to furnish a most remarkable instance of the lines 

 along which evolution has proceeded. The study is unfor- 

 tunately looked on with suspicion by biologists, on account 

 of our ignorance of the soft parts of these creatures, but 

 as a compensation for this, we do possess a true key of 

 the order of succession of the forms, obtained by actual 

 observation in the field, and not by speculative groping in 

 the study and laboratory. The material for the study 

 of the phylogeny of the trilobites is less complete than 

 that which we possess in the case of the graptolites, 

 but every year is adding to our knowledge of this group, 

 and we may confidently await a mass of information 

 furnished by a combined study in the field and under 

 the microscope of the corals, stromatoporoids and other 

 organisms. 



The above are only a few familiar examples of the 

 kind of work which has been done in elucidating geo- 

 logical problems, work which depends for its successful 

 issue upon detailed observations of the order of suc- 

 cession of the strata. Labours of a similar character 

 have been carried out in many parts of the world, and the 

 result is a very marked advance in all branches of geolooy 

 during the last two decades. And stratigraphical geolooy, 

 whilst giving valuable assistance to the other departments 



