no SCIENCE PROGRESS. 



hopeful one, and cannot fail to attract the attention, if not 

 the actual co-operation, of those interested in the broader 

 problems of botanical research. 



The examination of fossil organisms has not infrequently 

 led to the recognition of certain characters suggestive of a 

 combination of features now separated in distinct families. 

 Even before the publication of the 07'ig-m of Species, the 

 existence of generalised, synthetic, or prophetic types had 

 been hinted at, and in more recent times the interest attached 

 to such fossil forms has considerably increased. In searching 

 for the ancestors of living forms we may sometimes arrive 

 at a point where branching lines of affinity converge, and 

 point back towards some generalised pre-existing stock. 

 The recognition of any such synthetic forms, when based 

 on trustworthy evidence, marks a great advance, and 

 furnishes a far more valuable contribution to the history 

 of organic evolution, than does the construction of genea- 

 logies which rest to a large extent on pure assumption, and 

 appeal but little to the well-regulated scientific mind. It is 

 true there are to be found in palaeobotanical literature gene- 

 ralisations enough based on imperfect data as to the existence 

 of supposed synthetic types ; to refer to a plant which is 

 imperfectly known and litde understood, as combining in 

 itself the characteristics of distinct groups, is often a con- 

 venient method of coming to a conclusion. Fortunately in 

 not a few cases the evidence on which generalised forms 

 have been described is as sound and conclusive as evidence 

 can be. 



No better illustration of such synthetic types can be 

 described, than those recendy dealt with in a most able 

 manner in the pages of the Philosophical Transactions by 

 the late Professor Williamson and Dr. D. H. Scott. In 

 their memoir on the genera Lyginodendron and Heterangium 

 the authors have contributed to botanical science results of 

 exceptional importance,, demonstrating in the clearest manner 

 the possibilities of palaeobotanical work when carried out 

 on strictly scientific lines, and aided by a wide and accurate 

 knowledge of the morphology of recent plants. We may 

 best express the nature of those two Paleozoic fossil plants 



