Maryland Geological Survey 155 



The foregoing constitute about 40 per cent of the whole flora, and 

 none of these occur outside of North America except the Kuffordia, which 

 is a widespread Wealden type. 



The Arundel flora numbering 33 species contains the following species 



which are not present in the older Patuxent or the younger Patapsco 



floras: 



Thinnfeldia marylandica 

 Cycadeospermum marylandicum 

 Roger sia angustifolia parva 

 Cedrus Leei 



With the exception of these four species, together with Cycadeosper- 

 mum ohovatum, all of the species which are recorded from the Arundel 

 formation are common in the Patuxent, while these 4 species and 13 

 additional forms have not been found in the younger Patapsco flora. 

 The relation of the Arundel to the Patuxent formation is, however, much 

 closer than these figures indicate, since 24 Patuxent species which have 

 not been detected in the x\rundel survive in the Patapsco, and therefore 

 must have been present during the deposition of the Arundel, but 

 failed to be preserved or discovered. This leaves the five species 

 enumerated above as the sole distinction between the Patuxent and 

 Arundel floras, and with the exception of the unique Cedrus Leei all 

 are older genera well represented by closely allied species in the 

 Patuxent, as well as in other early Cretaceous floras. It is quite 

 probable that if the Arundel flora were more extensively preserved other 

 peculiar types would be discovered, nevertheless it is perfectly appar- 

 ent that the Arundel flora is closely allied to the flora which preceded 

 it, and the interval separating the two floras, if there was such an 

 interval, was one of short duration. This is strikingly confirmed by the 

 relations existing in the western interior between the Patuxent- Arundel 

 flora, as developed in the Kootanie formation of Montana and British 

 Columbia, and the Arundel vertebrate fauna which finds its closest simi- 

 larity in the Morrison (Atlantosaurus, Como) fauna. 



The two floras have a great many elements in common, and upon the 

 basis of the floras alone the conclusion would be reached that the base 



