192 THE POTOMAC OR YOUNGER MESOZOIC FLORA. 



the fragment were 14"" by 12"'". The tapering to tlae top is caused mainly 

 by a slope of one face of the trunk, viz, that shown on the right-hand 

 side on PI. CLXXIX, and hence the terminal bud, or that of growth, is 

 thrown much to one side of the axis of the trunk. A large terminal bud 

 may be seen on the highest part of the trunk, and on one side of this is 

 the break spoken of, which slopes down the trunk just as if the base of a 

 stem had been torn off. It is quite possible that this may have been a 

 stalk bearing the male inflorescence. If so, the trunk would be that of the 

 male plant, and the structural differences from those of No. 1 would be 

 accounted for by the sexual distinction. 



In both No. 1 and No. 2 the growth seems to have been maintained 

 by the development of successive circles of leaves at the summit of the 

 trunk which unfolded from a bud composed of vmdeveloped leaves, and 

 not from a terminal bud inclosed by bud scales, as Saporta holds to be the 

 case with his genus Clatliropodium. The fracture may be seen on PI. 

 CLXXIX, near the top of the trunk on the left hand, and very distinctly 

 on PI. CLXXX in front near the top. Trunk No. 2 shows none of the 

 larger lateral or axillary growths- or buds such as are so common in No. 1. 

 Near the top are faint indications of what may have been two small unde- 

 veloped leaf-buds without woody axis, but they are too obscure for us to 

 conclude positively that they are buds of any kind. They are composed 

 of circles of very minute apparent leaf-scars, which are much smaller than 

 those similarly placed in No. 1 and not near so distinct as these. 



The hollow casts left by the bases of the petioles indicate that these 

 had normally, in cross -section, the same shape as those of trunk No. 1. 

 But there is a greater tendency than in No. 1 for the upper side to be bent 

 in the form of an angle and thus give the cross-section a rhombic shape. 

 Some of the imprints are a good deal larger than tlie others, but the varia- 

 tions are due to distortions from pressure. The average dimensions of the 

 cross -sections are 22°"" by 12""". 



Fragment No. 2. 



This specimen, found at Spring Garden, measures in its greatest length 

 27'"', and in its greatest width 23"™, being in the shape of an irregular prism 



