DESCltlPTlON OF THE Si'EClKS. 185 



gin, very remote, obtusely rounded off at the tips, comparatively short, 

 bases of the leaflets thickened and callous when torn off,*and when the 

 midrib is compressed, leaving a depressed scar. 



Locality: Left bank of Dutch Grap (^anal ; ran;. 



The figure gives a portion only of the large specimen t'ouiid. 'I'lic 

 specimen is 20''" long, and shows no decided diminution in the size of the 

 midrib or in the lengths of the leaflets ; but the leaflets at the summit of 

 the stem are only half as far apart as those at bottom ; seventeen leaflets 

 occurred on the portion found. 



DiOONITES BUCIIIANUS, var. ANGUSTIFOLIUS. 



I'lirophijUum abieliniim Giipp., Danker. Mon. der iiorddeutscli. Woaldoubild., PI. VII, Fij;. 2. 

 Viuonitm abielhiim Miquel, Scheuk. Flor. der uordwi'stdeutsoli. Wcaldeiifonii., PI. XVI, Fig. 1. 



Plate LXVII, Fig. C; Plate LXVIII, Fig. 1 ; Plate LXXI, Fig. !i. 



Leaflets and nerves as in the normal form 1). JJucJiianius, except that 

 they are much narrower in the lower })arts of the leaves. 



Localities: Dutch Gap, especially at the fishing-hut above the canal : 

 Kankey's ; crossing of the Occoquan ; near Telegraph Station. 



These leaflets, as those of the normal species, vary a good deal in the 

 distances apart at which they are placed. In PI. LXVII, Fig. G, they are 

 very remote ; in PI. LXXI, P^ig. 2, they are very close together. The 

 forms that are placed in this variety show throughout the leaf naiTow leaf- 

 lets, and they do not seem to l)e mere accidentally narrow forms of the 

 typical plant. They never graduate into the wider leaf forms. 



This narrow leaf variety seems to be the same with the Wealden plant 

 figured by Schenk as Dloonltcs ahk'thius Miquel, in his Wealden flora, i'l. 

 XVI, Fig. 1. It appears also to be identical with the fossil given by Dun- 

 ker as Ptcrophyllum ahiefiintm Giipp. Hosius and Von der Marck' give a 

 figure of what they call I), ahiefiiius, which is exacth' like some of the 

 specimens of this Potomac fossil. The figure of the Westphalian fossil 

 represents a plant distorted by pressure. It comes from the Neocomian 

 sandstone of the Teuterburiier Wald. 



1 Flor. der Westfal. Kreidelormation, PI. XLIV, Fig. 199. 



