68 THE POTOMAC OR YOUNGER MESOZOIO FLORA. 



them as Asplenium, Dicksonia, etc., when they have no fructification and 

 are found in countries far remote from the supposed fructified forms. For 

 the reasons given above, the generic name Cladophlehis is retained for Meso- 

 zoic fossil ferns which possess the character given by Schimper, amended 

 as suggested. 



Cladophlebis constricta, sp. nov. 



Plate II, Fig. 11 ; Plate III, Fig. -2 ; Plate VI, Figs. .^>, fi, 8-14 ; Plate XXI, Figs. 9, 13 ; Plate CLXIX, Fig. 2. 



Frond bipinnate or tripinnate, arborescent; principal rachis slender; 

 primary pinnae remotely placed, very rapidly becoming shorter in ascend- 

 iug; ultimate pinnae very remotely placed, alternate, in the lower part of 

 the frond pinnately lobed; in ascending on the frond abruptly passing 

 first into pinnules with undulate margins and then into those with entire 

 margins; pinnules mostly very remotely placed, thick and leathery, alter- 

 nate, at their tips subacute or obtusely rounded, often constricted at base ; 

 in shape oblong to ovate; the midnerves of the pinnules towards their 

 summits split up into branches. The lower lateral nerves are once or 

 twice forked, the upper ones once forked. 



Localities: Fredericksburg; 72d mile-post, near Brooke: Deep Bot- 

 tom; Covington street, Baltimore. In all these places rare. 



I have united in this species a number of forms which differ some- 

 what in facies, but not enough to form the basis of specific separation. 

 In PI. XXI, Figs. 9, 13, are given two small fragments coming from Deep 

 Bottom, being the only specimens found there. They are thick and 

 leathery in character, and differ considerably from the fine specimen 

 given in PI. II, Fig. 11, which comes from Fredericksburg. The small 

 fragment depicted in PI. CLXIX, Fig. 2, comes from Covington street, 

 Baltimore. This also is leathery in character, and is much smaller than 

 most of the normal forms. The forms given in PI. VI, Figs. 3, 12-14, come 

 from the 72d mile-post, near Brooke. Their texture is ver}^ leathery and 

 thick, and the general character of the pinnules is not exactly that of the 

 type form, which may be considered as given in PI. II, Fig. 11. PI. VI, 

 Fig. 9, gives a small fragment from Fredericksburg which in facies is 

 much like a Gkiclienia, and is quite aberrant. 



