230 Revieics — A. C. Seioard's Fossil Plants. 



during the past fifty years if we had not maintained a school of 

 pal£8ontologists, who have kept alive an interest in fossil remains, 

 and who have been content to study and describe, to the best of 

 their ability, even the imperfect specimens which were obtained, 

 without waiting for the perfect materials which were not attainable ? 



Referring to the dual aspect of palgeontology, as treated of by 

 the biologist and the geologist, Mr. Seward appropriately quotes 

 Hnmboldt, who fifty years ago wrote : " The analytical study of 

 primitive animal and vegetable life has taken a double direction. 

 The one is purely morphological, and embraces especially the natural 

 history and physiology of organisms, filling up chasms in the series 

 of still living species by the fossil structures of the primitive world. 

 The second is more specially geognostic, considering fossil remains 

 in their relations to the superposition and relative age of the 

 sedimentary formations." To this we might now add that the 

 one furnishes a guide to the past history and records the modifi- 

 cations which the ancestors of still living forms have undergone ; 

 the other shows us the life-range of each form in time and often 

 its former distribution over the earth as well. 



On the subject of " Fossil Plants and Distribution " we 

 cordially agree with the author. " The present distribution of 

 plants and animals represents one chapter in the history of life on 

 the earth ; and to understand or appreciate the facts which it 

 records we have to look back through such pages as have been 



deciphered in the earlier chapters of the volume In 



the case of particular genera the study of the distribution of the 

 former species, both in time and space, that is geologically and 

 geographically, points to rational explanations of, or gives added 

 significance to, the facts of present-day distribution. That isolated 

 conifer, Ginkgo biloba, L., now restricted to Japan and China, was 

 in former times abundant in Europe and in other parts of the world. 

 It is clearly an exceedingly ancient type, isolated not only in 

 geographical distribution but in botanical affinities, which has 

 reached the last stage in its natural life. The mammoth trees of 

 California (Sequoia sempervirens and S. gigantea) afford other 

 examples of a parallel case." ^ 



The author takes us through a chapter on Geological History 

 showing how strata have been built up ; and then one on the 

 preservation of plants as fossils. Both these subjects are carefully 

 illustrated, and the student onght to be able to grasp some very good 

 and clear notions on these subjects as he reads this part of the book. 



A tougher chapter follows (v) " On the Difficulties and Sources 

 of Error in the Determination of Fossil Plants," all of which is 

 excellent reading ; but the student working at the present day with 

 the vast added lights invented for him in the past thirty or forty 

 years, need not, like the Pharisee of old, thank God for his 

 more exalted position to-day, nor forget entirely that but for the 



^ See the eloquent address by Professor Asa Gray to the American Association : 

 Silliman's Amer. Journal, Uctober, 1872, p. 282. 



