THE FOSSIL FLORA OF THE YORKSHIRE COAL FIELD. 207 



1877. Pecopteris silesiaca, var. Lebour. Illastr. of Fossil Plants, p. 53, pi. xxvi. 



1838. Steffensia silesiaca, Presl in Sternb. Vers. ii. p. 122. 



1854. Pecopteris Glockeriana, Ett. (Gopp. (?) ). Steinkf. v. Radnitz., p. 44, pi. xvii. fig. 1. 



1854. Pecopteris angustifida, Ett. Steinkf. v. Radnitz., p. 45, pi. xvi. fig. 1. 



Description. — Frond very large, much divided, tripinnate or quadripirmate. Pinnae 

 alternate. Primary pinna broadly lanceolate. Secondary pinnae lanceolate or linear- 

 lanceolate, often slightly overlapping, the central portion the widest, ending in a sharp 

 point and slightly narrowed at the base ; the central portion often of about equal width 

 for ^ of the length of the pinna. Tertiary pinnae linear-lanceolate, tapering to a 

 bluntish apex, the basal portion being usually the broadest. The lower portion of the 

 frond probably becomes quadripinnate. The large pinnae are subtended by two stipular- 

 like Aphlebia which spring from the anterior and posterior sides of the rachis. These 

 are adpressed to the rachis, but, being directed upwards and outwards laterally, hold 

 between them the base of the pinna they subtend. In general outline they are deltoid 

 or sub-orbicular, and are composed of narrow much divided sharp-pointed linear 

 segments without any apparent nervation. 



Pinnules alternate, and varying much in form, size, and pinnule cutting, according to 

 the position they hold on the frond being entire, dentate, or divided into teeth-like lobes. 



The pinnules on the middle tertiary pinnae are oval, triangular, or broadly lanceolate, 

 with rounded apices, united by their whole base to the rachis. The basal inferior 

 pinnule is deltoid — rounded, generally smaller than the others, and occupies the angle 

 formed by the insertion of the rachis of the pinna with its parent stem ; it bears a 

 distinctly marked lobe on the margin next to the parent rachis. The basal superior 

 pinnule is oval or oval-oblong, obtuse, and is the largest pinnule on the pinna. The upper 

 pinnules become gradually united in their basal portions and form a more or less lobecl, 

 — and finally, an entire blunt apex to the pinna. As the pinnae are traced upwards, 

 through the union of pinnules amongst themselves, the pinnae become simply lobed or 

 dentate, and in some cases assume the form of oblong or linear entire pinnules. As the 

 pinnae are traced downwards towards the base of the frond, the pinnules on the tertiary 

 pinnae become more and more distinctly lobed, till they almost assume the form of 

 small quadripinnate pinnae. 



The lateral veins in the basal pinnules of the lower tertiary pinnae are generally once 

 divided, — in the pinnules of the upper portion, the veins are usually simple ; 

 frequently, in the same pinnule, the lower lateral veins are divided, while the upper are 

 simple. In the dentate pinnules usually each lobe has a bifurcated veinlet, and in the 

 toothed pinnules of the lower pinnae a simple vein runs into each tooth. 



The fructification consists of exannulate oval or oval-acute sporangia, varying in 

 length from "50 mm. to *65 mm., and formed of coriaceous elongated cells. The 

 sporangia are placed upon, and parallel with, the lateral veinlets at a short distance 

 above their point of origin. Frequently the sporangia occupy the whole of the space 

 between the midrib and the margin of the pinnule. When the fructification is copiously 



