54 THE OLDEE MESOZOIC FLOEA OF VIEGINIA. 



broader and more obtuse, while they are united higher up than in Fig. 1. 

 Fig. 2 gives another form of lobes, and Fig. 3 still another. The plant must 

 have been rather variable in the shape of the lobes and in the amount of 

 their union. The middle nerve is quite distinct and strong toward the base 

 of the lobes, but disappears above the middle of these. The lateral nerves, 

 which by their anastomosis form the network of veins which fills the 

 lamina of the lobe, are very strong and sharply defined, so that they are 

 distinctly visible even on rather coarse-grained sandstones. The elongate 

 meshes often, owing to the compression to which the specimens have been 

 subjected in the rock, appear convex and cause the lobes to appear mamil- 

 lated. This plant resembles more closely than any others the Lonchopterids 

 of the Carboniferous formation. It resembles Lonchopteris rugosa, Brongt., 

 from Anzin, France, and Lonchopteris Bohlii, Andr., from near Aix-la-Cha- 

 pelle. It has some resemblance, except in the details of the nervation, to 

 Emmons's Acrostichites oblongus, Am. Greol, plate 4, fig. 8. 



Formation and locality. — Found at Manakin, in the material taken out of 

 the Aspinwall Shaft, and at Clover Hill. From this last locality the speci- 

 mens figured in Plates XXVII and XXIX were obtained. Occurs here only 

 in a siliceous sandstone of gray color with Clathropteris, and other plants 

 not found in any other beds below the main coal seam. The horizon is 

 probably that between the bottom and main seam. 



CLATHEOPTEEIS, Brongt. 



Clathropteris platyphylla, var. expansa, Saporta. 



Plate XXXI, Figs. 3 and 4; Plate XXXII, Fig. 1; Plate XXXIII, Fig. 1; Plate XXXT7, Fig. 1; Plate 



XXXV, Fig. 2. 



Frond digitately pinnatifld. Primary segments or lobes, at least six, united at 

 base, and diverging in a palmate manner, oblong, 30 centimeters and more long, aver- 

 age width 8 to 10 centimeters, extreme width 20 centimeters, with broad, shallow cre- 

 nate teeth along the margins. Primary nerves, or rachises of the segments, very 

 strong and prominent, the central ones single, the outer one on each side sending off 

 branches outwardly. These branches, and the central unbranched rachises, pass one 

 into each segment, forming its midrib. Secondary nerves, or lateral nerves of the 

 segments, in the united portions of the segments, rather slender, and going off under 

 an acute angle, those of the free portion of the segments, strong, rigid, prominent, 

 going off nearly or quite at a right angle, curving upward towards the ends of the 

 lobes or segments, and directed into the teeth along the margin, but ceasing before 



