DESCRIPTION OF SPECIES. 27 



but a careful inspection of the shape of the pinnules, and the plan of the 

 nervation, would soon convince one that these forms are essentially the 

 same with the fructified plant called, by Bunbury, Neuropteris linncecefolia. 

 I have never found the sterile or fertile forms anywhere but at this shaft. 

 Bunbury obtained his plant from the Blackheath Mine, which is in the same 

 vicinity. I give in Plate VI, Fig. 3, and Plate VIII, Fig. 1, representations 

 of the sterile frond. One of the forms (Plate VI, Fig. 3) has the pinnules 

 more bluntly terminated and a stouter principal rachis, indicating that the 

 specimen belongs to the lower portion of the frond. Plate VIII, Fig. 1, 

 represents a portion higher up on the frond, where the pinnules are more 

 acute, elongate, and falcate. Plate VI, Fig. 3 a, represents a magnified 

 portion of Fig. 3, giving the nervation, while in Plate VIII, Fig. 1 a, mag- 

 nified pinnules of Fig. 1 are represented. In both forms the pinnae are 

 closely placed, and overlap one another. The base of the pinnules of both 

 forms is slightly rounded on each side. A slight modification of both kinds 

 of pinnules, shortening and rounding them, would give us the form of the 

 pinnules of the fertile frond. Hence, even without the aid of the transi- 

 tion pinnules, such as are shown in Plate VII, Fig. 4, there would be no 

 difficulty in identifying these sterile forms as belonging to the same plant 

 as the form described by Bunbury. The consolidation of the pinnules in 

 becoming fructified, by being shortened and rounded, seems to be a not 

 uncommon feature in Acrostichides. It is shown in the Acrostichites Gcep- 

 pertianus of Schenk, and more markedly in Acrostichides rhombifolius to be 

 presently described. It will be noted that Schenk's plant shows the same 

 channeling of the stem as appears in our plant. This feature also is seen 

 in A. rhombifolius in a very marked manner. It does not appear in Plate 

 VIII, Fig. 1, for here the lower side of the rachis is no doubt seen, and this 

 is rounded or convex. 



These sterile forms of Acrostichides linncecefolius are no doubt the same 

 plant as that described by Bunbury, and also by Rogers, as Pecopteris 

 Whitbiensis. They have a marked resemblance to some of Brongniart's 

 figures of this plant, and this is especially true of the form delineated in 

 Plate VIII, Fig. 1. I may perhaps be permitted to remark in this connec- 

 tion that it seems to me that some authors have gone too far in identifying 



