108 FREDERICK ORPEN BOWER 



though not necessarily to any demonstration of its prime origin. 

 When we look round upon the great divisions of the plant king- 

 dom, it is at once realised how rarely these conditions are fully met. 

 The Algae and Fungi have virtually no consecutive fossil record 

 known as yet, while the deficiency of their anatomical characters 

 throws comparison chiefly upon their organs of propagation: so 

 that notwithstanding the wealth of species their phyletic study 

 presents difficulties. The Liverworts and Mosses are alike with- 

 out any reliable Palaeontology. The former present more hope- 

 ful characters for comparison of living forms than the latter, for 

 these suffer from their relatively dead level of uniformity, except 

 in characters that are almost minimal. The Lycopods and Equi- 

 seta were both of exceedingly ancient origin, antedating the 

 palseontological record in most of their salient characters. Never- 

 theless the fair representation of living species both of Lycopo- 

 dium and Selaginella gives a fair opening for comparative study, 

 which has not been neglected. The Gymnospermic state was 

 already established in times prior to the earliest dependable facts 

 of palaeontology, and though'the fossil record helps in many points, 

 still the gaps in it, as well as the isolation of many of the living 

 types have made their phyletic study full of problems. And lastly 

 the Angiosperms, with their plethora of living representatives, have 

 so recent and so imperfect a fossil record that, in face of the lack 

 of settled canons of critical treatment of those living, their phy- 

 letic arrangement is still chaotic, and views of their descent very 

 divergent. 



None of these large divisions of the plant kingdom answer 

 the requirements stated above so fully as do the Filicales. We 

 find them to have a fossil record which is hardly matched in its 

 extent and in its consecutive character. They are represented 

 at the present day by a wealth of species, grouped in well-defined 

 genera and families. They show a great variety of characters, 

 which are a suitable basis for comparison, while the fossil record 

 shows certain of them to have been progressive through the ages. 

 Putting on one side the Eusporangiate types (whose isolation and 

 paucity of species, as well as the ancient origin of some of them, 

 render them problematical in their phyletic relation), it may be 



