56 THE OLDER MESOZOIC FLORA OF VIRGINIA. 



panse of the frond. On this specimen traces of the secondary nervation 

 may be seen, and its slenderness and oblique nature in the united parts 

 may be discovered. In Plate XXXIII, Fig. 1, we have fragments of three 

 central primary rachises, and one outer one on the left-hand side. This 

 outer one is seen to send off two branches, directed outwards into the left- 

 hand border of the frond. It is much stronger than the central rachises. 

 The inner one next to this branching rachis, has its base closely pressed 

 against the base of the outer rachis in a manner which might, to the casual 

 observer, suggest that the two branch from this point. The close approx- 

 imation results from a crush which has affected the lower portion of this 

 fragment. The union of this inner rachis and the branching outer one 

 takes place lower down, in a portion of the frond not visible in the speci- 

 men. The entire fragment given in Plate XXXIII, Fig. 1 , seems to belong 

 to the united portion of the lobes, and, if so, this part of the frond must 

 have had very considerable dimensions. 



It will be seen from this account of the plant that it differs in several 

 points from the normal Clathropteris platyphylla as found in Europe, and de- 

 scribed by Schenk, Schimper, and others. But in all the points in which it 

 differs from the normal form, it approaches the variety expansa, described 

 by Saporta in "Plantes jurass.," and figured on Plate XXXVIII, Figs. 3, 4; 

 Plate XXXIX, Fig. 1; Plate XL, Fig. 1. Saporta's plant is from the Infra- 

 Lias, near Autun, France. The French plant has the same characters as the 

 Virginia one. We find in it the same prominent rigid rachises of the seg- 

 ments. The secondary nerves go off nearly or quite at a right angle, and 

 curve up towards the summit of the segments. The character of the teeth 

 is exactly the same with that of the Virginia plant. Saporta says that the 

 plant he describes is larger than the normal German C. platyphylla. The 

 average size of the Virginia plant is the same with that of the French one. 

 But the largest specimen of the Virginia fossil is considerably larger than 

 any of the specimens given by Saporta. In Saporta's plant the secondary 

 nerves terminate in the tips of the teeth, on the margin of the segments, 

 while they appear to terminate in the Virginia fossil before reaching the 

 extremity of the teeth. The ultimate nervation of the French plant in 

 some specimens seems to be rather more irregular than that of the Virginia 



