5<j6 MESOZOIC FLORAS OF UXnED STATES. 



than 150 specimens of it, occurring in most of the collections. As in the 



case of the leaves which were the basis of the description given in Mono- 



gi-aph X\\ they are mostly fragmentary and detached. The texture of 



the leaves seems to have been, although rathei' thick, unfavorable for 



presentation. At least not a single one of the numerous specimens that 



have been found is an entire leaf. The figures of this species given in 



Monograph XV show that there is a considerable variation in the size of 



the leaves, the shape of the lobes, and in their num])er. It is possible that 



there is more than one species in the leaves assigned to this species, but the 



variations appear inconstant, and they graduate into one another in such 



a way as to make it impossible to separate them. PI. CXIX, Fig. 2, 



gives a leaf unusually large. Figs. 3, 4 represent leaves of average size, 



which, taken together, may give a pretty good idea of their shape. The 



specimen shown in Fig. 2 occurs in collection No. 5 and is W. C, B., 



Xo. 5961. The two leaves represented in Figs. 3 and 4 are on the same 



side of one large slab, which is W. C, B., Xo. 6242. It occurs in collection 



Xo. 4, without date. 



Ament of conifer (b). 



In IMonograph XV a numl)er of aments of conifers are described which 

 could not be connected with any species based upon foliage. These were 

 designated by the letters of the alphabet, as ament of conifer (a), etc. 

 The ament designated ament (b)" seems to be present in the collections 

 from Covington and Clement streets. It is represented by a single 

 detached form. It must, from this, have been veiy rare in the flora. The 

 specimen occurs in collection No. 5 and is W. C, B., No. 5976. 



AGE OF THE FEDERAL HIIX BEDS. 



The plants obtained from the horizon of the strata of Federal Hill 

 show some features that make it difficult to determine satisfactorily their 

 age by a comparison with those described in Monograph XV. from the 

 Lower Potomac of Virginia. This will ))est be shown l)v an examination 

 in some detail of the list of plants obtained at the Baltimore localities. 



For the puipose of comparison with the Virginia plants, all those 

 doul)tfully determined and those coming from the Baltimore localities 



o Monograph XV, p. 22.1, pi. cx.xxvi, fig. 3. 



