EXPLANATION OF PLATES. 191 



PLATE IV. 



DiCTYOPHYTON NEWBERRYI. 



^ Fig. 1. A nearly entire frond of this species. The lower part is a little imperfect, that 

 portion remaining showing an apparent fibrous structure resembling root- 

 lets. 

 /^ <« 2. A cast of the interior of the expanded portion of the frond of this species. In 

 the specimen fig. 1, the upper funnel-shaped portion of the frond shows a 

 tendency to separate from the stem below, producing a form shnilar to thia 

 one. 



l^ <« 3. The stem of a large individual of this species? 



/> « 4. A portion of the surface from another stem, where the markings are well 

 '^ preserved. 



DiCTYOPHYTON FILITEXTILE. 

 / 



Fig. 6. A figure from a cast made in a natural mould in sandstone. In the figure, 

 some of the transverse lines are comparatively too strong. 



DiCTYOPHYTON REDFIELDI? 

 V Fig. 6. A fragment of a stem which belongs, apparently, to this species. 



