cockerell: lower cretaceous flora 



111 



pinnae which I refer with confidence to Matonidium althausii 

 (Dunker) Ward. Although the sori, from the nature of the sand- 

 stone matrix, are poorly preserved, the structure appears to 

 agree exactly with this species, especially as figured by Seward. 5 

 Dr. Seward, also, after examining the photographs, states that 

 he has little doubt that the specimens belong to Matonidium. 

 This plant is a fern of peculiar interest, as it appears to be the 

 ancestor of the isolated modern genus Matonia, found in Borneo 

 and the Malay peninsula. Matonidium althausii is a well-known 

 European fossil, but the Colorado specimens present no differ- 

 ences that can be seen. 



The collection also 

 contains some ferns 

 which agree very well 

 with Todites, so far as 

 appearances go, but 

 there are no sori, and 

 exact determination is 

 not possible. Some 

 specimens could belong 

 to Weichselia, or even 

 better, as Dr. Berry 

 suggests, to Cladophle- 

 bis. One fragment ap- 

 pears to agree exactly with Onychiopsis. 



Searching for a corresponding flora in the records, we find 

 the nearest approach in the Fuson formation of the Black Hills, 

 from which 26 species have been recorded by Ward and Fontaine. 6 

 The Fuson list contains Matonidium althausii, Sapindopsis 

 variabilis, Equisetum burchardti, Cladophlebis, and Weichselia. 

 According to Berry this is approximately contemporaneous 

 with the Patapsco of Maryland and Virginia; which, however, 

 contains a much greater variety of angiosperms. The Fuson 

 list includes, in addition to Sapindopsis, fragments referred to 

 Ulmiphyllum, Qaercophyllum, and Ficophyllum. Berry notes 



5 Jurassic Flora. I. The Yorkshire Coast, 76. fig. 7A. 1900. 



6 U. S. Geol. Surv., 19th Ann. Rept., pt. 2. 1899. 



Fig. 2. Matonidium althausii (Dunker) Ward. 

 About natural size. 



