DESCEIPTION OF SPECIES. 79 



his account of them, those of this plant. The leaflets of this plant are very 

 deciduous, and it is a very rare thing that they are found attached to a stem. 

 They usually appear scattered over the surface of the shale, and the stems, 

 quite bare of leaflets, or containing only one or two, are to be seen mingled 

 with the dispersed leaflets. Fig. 3 represents quite a common form in which 

 the leaflets have the smallest size found in the species. In Fig. 3 the rough 

 irregularly striate midrib is shown, and the slight prominences which mark 

 the bases of the pedicels. Fig. 3 a gives an enlarged leaflet with nervation, 

 and Fig. 3 b, the summit of the same still more enlarged. Fig. 2 represents 

 a larger form of the leaflets. Here they vary in shape from those seen in 

 Fig. 3. They are larger and more uniform in width. Fig. 5 gives a leaflet 

 of this form of the largest size. Fig. 4 gives a form obtained from the Cum- 

 berland Area near Farmville, in which the leaflets appear to have their 

 pedicels placed more on the upper face of the midrib than in the normal 

 forms, where they are attached on the sides. This mode of attachment may 

 result from the mode of preservation of the specimen. This small species 

 is evidently of the same type with Podozamites Emmonsi, and the two differ 

 quite considerably from all previously described forms of Podozamites. 



Formation and locality. — This plant is the most abundant form of Podoza- 

 mites found in the Virginia Mesozoic and is widely diffused. It is one of 

 the few plants found in the Cumberland area, and it occurs at all the local- 

 ities yielding plants in the Richmond Coal Field. It is not uncommon in 

 the form of scattered leaflets at Carbon Hill, Midlothian, Clover Hill, and 

 Deep Run, occurring in the shales between the lower and the main coal 

 seams. These shales and sandstones overlying the lower coal appear to be 

 richer in plant impressions, and to have a greater number of species than 

 any other series of strata. 



SPHENOZAMITES, Brongt. 



Leaf pinnate, with usually a strong smooth stem; leaflets, the broader ones, large, 

 more or less narrowed at the base, equilateral, begirt with a narrow cartilaginous mar- 

 gin, entire or sinuate at the apex, and spinously dentate, inserted on, or near, the sides 

 of the midrib, always separate to the base, subpediceled, never covering the upper 

 surface of the midrib; nerves radiating from the place of insertion, numerous, and 

 several times branching dichotomously. 



