110 ON THE FOSSIL FLORA OF THE COAL DEPOSITS OF AUSTRALIA, 



sometimes confluent. Costa persistent to the apex, pinnately 

 ramose ; veins dichotomous diverging to the margin at a more or 

 less open angle. Venules simple, forking twice or thrice, rarely 

 anastomosing. When sori are present they are marginal or dis- 

 posed towards the middle of the pinnule, punctiform, oval or linear. 

 This order is established entirely upon the venation, and unites 

 the characters of very different living genera and families. On 

 this account the classification of the various forms in one intel- 

 ligible system has hitherto failed 



Pecopteris, Brongniart. 



Veins emerging from the costa in a more or less open angle, 

 diverging arcuately, simple or dichotomous, venules often forked. 



Pecopteris tenuifolia, M'Coy (Ann. Nat. Hist., vol. 20, p. 152, 

 PI. IX,, fig. 6.) Bi-pinnatifid (?) pinnules and rachis very slender, 

 each about half a line wide ; pinnules very long, oblique, linear, 

 apparently simply united to the rachis by their entire base, one 

 very strong costa running throughout, veins unknown. Obs. — 

 " If this be truly a fecopteris it is distinct from all others by its 

 very narrow linear leaflets. The only plant I have seen at all 

 resembling it is the Zamites obtusifolius from the shale of the 

 Oolitic coal fields, Blackheath, Richmond, United States, exhibited 

 some weeks since by Mr. Lyell to the Geological Society. The 

 specimens alluded to of this latter plant seem imperfectly pre- 

 served, but still show on some portions of the pinnules a neuration 

 running parallel with a strong midrib. This great costa seems to 

 me to be incompatible with Zamites, so that although I point to 

 the resemblance between the American and Australian plants, I 

 prefer placing the latter provisionally in Pecopteris, as I have seen 

 no trace in my imperfectly preserved specimens of a parallel vena- 

 tion, and even if it should hereafter be found to exist, I conceive 

 it would be necessary to form a new genus intermediate in form, 

 venation, and, I think, mode of attachment of the pinnules to the 

 rachis between Zamites and Pecopteris, for the reception of these 

 two plants. One specimen has occurred in the fine sandstone of 

 Clarke's Hill, N.S. Wales." 



