LYOOPODIALES— LEPIDODENDRE.g<:— LEPIDODENDEON. 197 



tapering into long, slender, filamentous tips that are lost in the meslies of the 

 cortex. The leaf scars situated jiist above the middle of the bolsters are 

 about one-half of the width of the bolsters, rhomboidal, the vertical and 

 lateral diagonals being nearly equal. The upper margins, which are a little 

 longer than the lower, are sometimes slightly concave, the upper, sKghtly 

 acute angle, being round or obscurely and narrowly emarginate, while the 

 lower margins are nearly at a right angle, the lateral and lower angles 

 being slightly rounded. A little above the leaf scar the ligular scar can 

 sometimes be seen Tlie three cicatricules within the leaf scar lie at the 

 same level, distinctly below the middle of the scar, the vascular cicatrix 

 being punctiform or slightly V-shaped, while the respiratory traces are 

 round-oval or oval, the lower ends inclined slightly inward. Traces of 

 respiratory appendages are not seen. 



A prominent feature of the fragment of stem, which seems wide in 

 proportion to the size of the bolsters, is the loosely and irregularly meshed 

 surface lines traversing the broad border. These lines, which are irregular 

 in interval and uneven in direction, mark the impressions of the bark as 

 sharp, nearly longitudinal, ridges. Although at first glance they appear to 

 lie in a general direction of parallelism to the borders of the bolsters, they 

 may readily be seen to consist of two oblique systems of ridges crossing at 

 a very acute angle. Thus, many of those from the upper margins of each 

 bolster appear to pass obliquely to the lower margins of the proximate 

 bolsters, higher on either side as is seen in Fig. 3a. The irregularity of the 

 size of the meshes is largely due to the variation in the distance between the 

 ridges and the somewhat irregular lines, combined with the interruptions 

 caused by the very long apices of the bolsters. 



Another specimen, said to have come from Clinton, Missouri, is illus- 

 trated in PI. LTV, Fig. 4. This fragment, No. 5280 of the Lacoe collection, 

 was identified as Lepidodendron rimostim by Professor Lesquereux. This 

 impression in sandstone shows well the aspect of the bolsters and meshes of 

 the cortex, and the low keels in the lower and upper fields. No transverse 

 lines mark the cauda. The photograph leaves nothing to add as to the leaf 

 scars, which are imperfect and without satisfactory details. 



The form represented by these two specimens appears to merit a 

 varietal differentiation. The new variety retocorticatum may therefore be 

 distinguished by the narrow bolsters, the proportionately greater altitude 



