DESCBIPTION OF SPECIES. 39 



tion of the plant in which the fructification is wanting. Fig. 3 a represents 

 a magnified pinnule of the same. Plate XIX, Fig. 1, represents a portion 

 of the frond as it appears when seen from the upper side, the entire leaf- 

 substance being preserved. As this is thick and coriaceous, the sori and 

 nerves do not appear distinctly. In this specimen no sori appear on the 

 pinnules of the upper pinnae. The ridged upper surface of the principal 

 rachis and the woody cord of the central portion of the ultimate pinnae are 

 plainly shown in this specimen. Plate XVII, Fig. 1, gives a portion of the 

 middle part of a sterile frond or primary pinna, Fig. 1 a represents the ner- 

 vation of a magnified pinnule of this specimen, and Fig. 1 b the heteromor- 

 phous pinnule as here shown. Plate XVII, Fig. 2, gives a portion of the 

 upper part of a sterile frond, and Fig. 2 a the nervation of a magnified pin- 

 nule of the same. Plate XVI, Fig. 3, gives a somewhat abnormal form of 

 the upper part of a sterile specimen where the pinnules are more ovate than 

 in the normal form, and the heteromorphous pinnule less heteromorphous 

 than usual. Plate XVI, Fig. 2, gives still another abnormal form. Plate 

 XV, Fig. 2, gives the normal form of the lower portion of a plant of large 

 size. Fig. 5, same plate, gives a fragment of a heteromorphous pinnule 

 seen detached from its rachis, and of natural size. It shows the great size 

 that, some of these pinnules attained. Plate XVI, Fig. 1, represents a fruc- 

 tified form of common occurrence, in which the sori of the upper pinnules 

 become few in number and are irregularly placed. Plate XVIII, Fig. 2, 

 represents a fully fructified form of the plant which is not uncommon. 

 Formation and locality. — Abundant in the shales and shaly sandstones 

 over the lower coal at Carbon Hill and Clover Hill; found also at the 

 Gowry shaft near Midlothian. Bunbury gives Deep Run in addition. 



Mertensides distans, spec. nov. 

 Plate XV, Fig. 1. 



Sterile frond not seen. Fertile frond bi- or tripinnate, perhaps arborescent. Frond, 

 or primary pinna, very long and apparently linear-lanceolate in outline. Ultimate 

 pinnae linear in shape, and subopposite. Pinnules thick and coriaceous, remotely 

 placed and alternate, standing nearly at right angles with -the rachis, very small, 

 ovate-oblong, subfalcate, inserted by the entire base, and bluntly rounded at the ends. 

 Nervation not disclosed. Fructification in the form of sori, composed of about 4 

 sporangia, grouped radially around an axis, and occupying the lower half of the 



