730 FOSSIL FLOEA. OF THE CARBONIFEROUS SYSTEM. 



tomical structure of the stems of these plants may have some effect 

 on the microscopic characters of the coal produced from them. ■ In 

 some cannel coals structure resembling that of aorogens has been 

 observed. A brownish-yeUow substance is occasionally present, which 

 seems to yield abundance of carburetted hydrogen gas when exposed 

 to heat. 



linger enumerates 683 plants of the Coal-measures, Schimper men- 

 tions 666, while Brongniart notices 500. Of the last number there 

 are 6 ThaUogens, 346 Acrogens, 135 Gymnosperms, and 13 doubtful 

 plants. This appears to be a very scanty vegetation, as far as regards 

 the number of species. It is only equal to about l-20th of the num- 

 ber of species now growing on the surface of the soil of Europe, 

 Although, however, the number of species was small, yet it is pro- 

 bable that the individuals of a species were numerous. The propor- 

 tion of Ferns was very large. There were between 200 and 300 

 enumerated. The following are some of the Oryptogamous and Phane- 

 rogamous genera belonging to the flora of the Carboniferous period : — 

 Cyclopteris, Neuropteris, Odontopteris, Sphenopteris, Hymenophyl- 

 lites, Alethopteris, Pecopteris, Coniopteris, Cladophlebis, Senftenber- 

 gia, Lonchopteris, Glossopteris, Oaulopteris, Lepidodendxon (Lepido- 

 strobus, Lepidophyllum), Lyginodendron (Dictyoxylon), Knorria, 

 Ulodendron, Halonia, Psaronius, SigUlaria and Stigmaria, Cala- 

 mites, Asterophyllites, SphenophyUum, Noggerathia, Peuce, Dadoxy- 

 lon, Araucarioxylon, Trigonocarpus. 



Ferns are the carboniferous fossil group which presents the most 

 obvious and recognisable relationship to an order of the present day. 

 While cellular plants and those with lax tissues lose their characters 

 by the maceration to which they were subjected before fossilisation 

 took place, ferns are more durable, and retain their structure. It is 

 rare, however, to find the stalk of the frond completely preserved 

 down to its base. It is also rare to find fructification present. In 

 this respect, fossil Ferns resemble Tree-ferns of the present day, the 

 fronds of which rarely exhibit fructification. Hooker states that of 

 two or three kinds of New Zealand Tree-ferns, not one specimen ia a 

 thousand bears a single fertile frond, though aU abound in barren ones. 

 Only one surface of the fossil Fern-frond is exposed, and that gener- 

 ally the least important in a botanical point of view. Fructification 

 is sometimes evidently seen, as figured by Oorda in Senftenbergia. 

 Mr. Carruthers has recently detected the separate sporangia of Ferns 

 full of spores in calcareous nodules in coal. These have the elastic 

 ring characteristic of the Polypodiacese, and in their size, form, and 

 method of attachment, they are allied to the group HymenophyUese. 

 The absence of fructification presents a great obstacle to the determi- 

 nation of fossil Ferns. Circinate vernation, so common in modem 

 Ferns, is rarely seen in the fossil species, and we do not in general 



