186 



THE FOSSIL TEENS. 



Leaf once, twice, or thrice, pinnate.; leaflets adhering by 

 their base to the rachis, or occasionally distinct; mid-rib 

 running quite through the leaflet ; veins almost perpendicular 

 to the mid-rib, simple, or once or twice dichotomous. 



Sixty species in the coal formation.* 



Two species in the lias. 



Ten species in the oolites. 



One species in the beds above the chalk. 



The accompanying figure is that of P. adiantoides (fig. 

 122), with magnified leaflet; from Lindley and Hutton, PL 37. 



LoncJiopteris, from Ao-y^o?, a spear, and nrepis, a fern. 



Leaf many times pinnatifid ; leaflets more or less connate 

 at the base, having a mid-rib ; veins reticulated. 



Two species in the coal formation. 



One species in the green sand formation. 

 One species in the Wealden. L. Mantelli (fig. 123). 

 Clathropteris, from xKetdpov, a lattice, and Trrepis, a fern. 

 Leaf deeply pinnatifid ; leaflets having a very strong com- 

 plete mid-rib ; veins numerous and simple, parallel, almost 



* See many plates in the Pict. Atlas. 



+ Fig. 1, a portion of three leaflets magnified ; fig. 2, part of a stem, with 

 leaves. 



