566 MESOZOIC FLORAS OF UNITED 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- 

 graph XV, they are mostly fragmentary and detached. The texture of 

 the leaves seems to have been, although rather thick, unfavorable for 

 preservation. 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 number. 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. PL CXIX, Fig. 2, 

 gives a leaf unusualh^ 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., 

 No. 5961. The two leaves represented in Figs. 3 and 4 are on the same 

 side of one large slab, which is W. C, B., No. 6242. It occurs in collection 

 No. 4, without date. 



Ament of conifer (b). 



In Monograph XV a number 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 very rare in the flora. The 

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



AGE OF THE FEDERAL HILL 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 best be shown by an examination 

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



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

 doubtfully determined and those coming from the Baltimore localities 



« Monograph XV, p. 225, pi. cx.xxvi, fig. 3. 



