WARD] DISCUSSION OP DIAGRAMS. 445 



argue from paleontology, and most of the points in which it differs from 

 accepted botanical systems have been independently confirmed by 

 structural botanists. 



More remarkable still, perhaps, than the early appearance of marine 

 algae is that of certain well-organized vascular plants that must have 

 inhabited the land. Among the earliest forms of terrestrial vegetation 

 we find the ferns, those graceful forms whose green, airy fronds are still 

 the delight of every judge of natural beauty. We have at least one 

 well-authenticated species in the Silurian — Hopteris Morierii of Saporta — 

 found by Morifere a few years ago at the base of the Middle Silurian, a 

 gilt figure of which its namer has made the frontispiece of one of his 

 last works.^^ The fern may be almost taken to represent the primary 

 form of the vegetative process. Its delicate spray resembles, most of 

 all plant-forms, the exquisite frost-work which we see on our windows on 

 a cold morning. The physicists tell us that these latter are the result 

 of molecular activities and consist in the deposit of solidified molecules 

 of invisible vapor. Plant^growth consists in the deposit of solidified 

 carbon molecules upon the growing surfaces of plants. Perhaps, then, 

 we should not wonder at the resemblance between the earliest forms of 

 plant life and those other forms which nature creates by the action of 

 the same principle, and which the chemist can imitate in certain modes 

 of precipitation. 



In the Devonian we have 79 species of ferns, and this type of vegeta- 

 tion reaches its maximum in the Carboniferous epoch, which, if we ex- 

 tend it to include the Subcarboniferous and the Permian, furnishes 877 

 species, forming nearly 45 per cent of the total flora of that epoch. 

 There are good reasons for supposing that during this age the ferns 

 were nearly all arborescent and really formed a large part of the Car- 

 boniferous forests. Prom this time forward they declined both in num- 

 ber and vigor until, at the present time, they are only 2 per cent of 

 the vegetation of the globe, and in nearly all cases consist of low 

 herbaceous plants, almost valueless except for their singular beauty. 



Let us next consider the type which is here denominated the Uquiseti- 

 nece. At the present time the natural order Uquisetacew embraces all 

 the plants of this group, and they are very few indeed and insignificant 

 in size, but in the Carboniferous age they formed nearly 10 per cent of the 

 vegetation, and furnished the great Calamites, which clearly show that 

 they were no mean element in the forest growth of that period. Certain 

 plants of this group — SpJienophyllum primcBVum, Annularia Bomingeri — 

 were found by Mr. Lesquereux in the Cincinnati group of the Silurian, 

 an horizon, perhaps, lower than that of Uopteris, and we must therefore 

 regard this type as of exceedingly ancient origin. The Calamites dis- 

 appear entirely in Mesozoic time and the type dwindles into insignifi- 

 cance. 



i'^Le Monde des Plantes avant I'apparition de I'homme. Paris, 1879. (See pp. 35, 166. ) 



