DESCRIPTION OF SPECIES. 37 



show the heteromorphous pinnule, as he does not give the portion of the 

 plant occupied by this pinnule in his figure in the article in the "Quarterly 

 Journal of the Geological Society." Bunbury's specimen has its pinnules 

 distorted by being pressed into the shale. They thus appear narrower at 

 base than they should be. 



This plant seems to be the same with the Pecopteris, compared by Pro- 

 fessor Rogers with Pecopteris obtusifolia of Lindl. and Hutt, but which he does 

 not name. Professor Rogers seems to have obtained a very imperfect speci- 

 men. The rachis of the ultimate pinnae is usually very broad and flat, and has 

 in its center a prominent woody portion, to which the middle nerves of the 

 pinnules are attached. This seems to be bordered by a thick leathery mar- 

 gin which may be really a sort of wing. The bases of the pinnules are 

 attached to this, but their middle nerves pass through it to join the woody 

 central axis. This axis is well shown in Plate XV, Fig. 2, where the margin 

 is quite wide, and makes the rachis appear to be very broad The princi- 

 pal rachis is quite strongly ridged on each side, and is often very strong, being 

 sometimes more than a centimeter wide. I have seen some fragments of the 

 primary pinna? that were over 45 centimeters long in which the spread of 

 the ultimate pinnae was 30 centimeters. These all appear to be pinna? 

 belonging to an arborescent plant. The upper pinnules, especially of the 

 sterile frond, are united for a considerable distance above their bases, while 

 the pinnules of the lower fertile pinnae become crenately lobed, and tend to 

 pass into pinnae. The shape of the fertile pinnides is very constant and 

 characteristic. They have a slightly expanded base, but above the base 

 are oblong, slightly falcate, and very bluntly rounded off, while they stand 

 nearly or quite at right angles to the rachis upon which they are inserted. 

 The sterile pinnules have a somewhat different shape. They have a pro- 

 portionally broader base, are more obliquely inserted, and are more acute 

 and falcate. The nervation is the same in both sterile and fertile pinnules, 

 and the heteromorphous pinnule is present in both sterile and fertile fronds. 

 This pinnule sometimes becomes very large, as is shown in Plate XV, Figs. 

 4, 5, both of natural size. 



The fructification shows many points of interest. As a rule the sori 

 are comparatively few, and irregularly scattered on the pinnules nearest the 



