1921] ROUND—ODONTOPTERIS 403 
dence, Pawtucket, Arlington, Cranston, and Warwick. These 
rocks are now in the collection of the geological department of Brown 
University. As they never appear waterworn it may be inferred 
that these plants fringed the coal: marshes of the Narragansett 
Basin in the Carboniferous, and were buried and fossilized near 
their places of growth. ‘Most of these fossiliferous materials are 
preserved in fine grained black shale. The specimen from Boyden 
Heights, however, is of sandstone, a material not generally fossil- 
iferous in the state except as the matrix of coarse forms like Cala- 
mites (fig. 3a). 
With such abundance of preserved material as is represented 
by O. genuina in Rhode Island, it seems significant that no fruited 
pinnae are in evidence. It has been proved by KipstTon,? however, 
that many of the so-called fossil “ferns”? were really Pteridosperms 
or Cycadofilicales. Many detached seeds are found in the rocks 
of Rhode Island, proof that the ancestors of modern flowering 
plants were denisons of the coal forests of the state, among which 
it seems probable that O. genuina may sometime be included. 
3 Kipston, R., Les végétaux houillers recueillis dans le Hainaut belge. Mém. 
Mus. Roy. Hist. Nat. Belg. 4:5. 1911. 
