On the Leaf Sears of Lepidodendron. 87 



L. modulatum? The specimen affording Fig. 1, PI. VIII, has a 

 portion of the vascular scars of normal shape and perfect. 



The triangular or crescent-shaped cicatrix above the vas- 

 cular scar, called the crown, is not often mentioned in 

 descriptions of this species. But it certainly is as prominent 

 and permanent as the appendages. The plates show its 

 various modifications. The figures of modulatum and distans 

 are liable to give a wrong idea of the shape and character of 

 this feature, to a person not familiar with the fossils. The in- 

 ferior or concave side of the crown is depressed below the 

 general surface of the leaf scar. In Figs. 4, 6, PI. VI, the two 

 lines between the crown and vascular scar, which give each 

 crown the appearance of two triangles joined at their bases, 

 only mark the boundaries of the triangular area between the 

 depressed side of the crown and the superior angle of the ele- 

 vated vascular scar. They are doubtless unduly prominent in 

 the two figures ; and they must be too prominent, if repre- 

 sented at all, in an outline drawing. Fig. 2, PI. V, and Fig. 

 3, PI. VI, show the same feature. Appendages to the crown 

 are sometimes found on specimens with strong relief and 

 sharp definition. The crown is easily obliterated. 



The middle one of the three vascular points, which is 

 elongated laterally, and is naturally larger than the puncti- 

 form lateral ones, is frequently much enlarged, while the 

 lateral ones are obsolete (Fig 3, PI. VI; Figs. 1, 3, PI. VII; 

 Fig. 2, PI. VIII). In some instances the lateral points are en- 

 larged at the expense of the middle one (Fig. 4, PI. VIII). It 

 is not rare to find the three points united by an elevated line 

 or wrinkle. L. modulatum is described as having the points 

 united by a depressed line ; but evidently the cast is described 

 instead of the cortex, as the margin is said to be elevated. 

 This line uniting the points, like many other passing features, 

 is not sufficiently permanent to be of value. 



The tubercles vary in shape from narrow elliptical to ovate, 

 or even subrotund. They may be parallel or diverging. Some- 

 times they seem to be easily effaced, and at other times very 

 enduring (Fig. 5, PI. VII). In small or young scars they are 

 often undeveloped. 



