THE CAHBONIFEROUS AND PERMIAN FLORAS. 453 



found in the coal-formation over almost the whole world. 

 In Alethoperis the leaflets are attached by their bases to 

 the stem and to one another, and are provided with a very 

 distinct midrib from which the veins are given off nearly at 

 right angles. The commonest species is the cosmopolitan 

 Alethopteris (Pecopteris) lonchitica, which nearly resembles 



705.— Neurojjteris heteropliyUa. Coal-iiieasuies of Europe. The lower figure 

 shows a siiiKle leaflet enlarged. 



the living Brackens {Pteris aquilincC). Nearly allied to 

 Alethopteris is the genus Pecopteris, which includes a large 

 number of characteristic Carboniferous species. In Oclonto- 

 pteris (fig. 706) the frond is pinnate, the leaflets being 

 attached by their entire bases, and the veins are generally 

 given off from the base. The species here figured is a 

 widely-distributed one, occurring in both Europe and North 



