2 86 THE AMERICAN MIDLAND NATURALIST 



Observations on Some Marine Plants of the Iowa Devonian, with 

 Descriptions of New Genera and Species. 



9 



BY CLEMENT L. WEBSTER, M. SC. 



Introduction. 



In most divisions of the rocks of the Iowa Devonian, there occu^ 

 at certain horizons from a few to great numbers of fossil marin^ 

 plants, nearly all of them apparently referable to the "seaweeds." 

 But little attention has thus far been paid to these most interesting 

 forms of ancient plant life by the workers in this field, and but 

 little reference to them has so far appeared in the literature of 

 Iowa Devonian geology. 



So far as certainly known, not a single species of any of these 

 plant forms occurring in the lower and middle Devonian of Iowa, 

 appears in the upper Devonian or Hackberry group. In all these 

 divisions various species of this or other class of plant life occur, 

 and sometimes the strata are crowded with their fossil remains. 

 One of these localities of special interest is that at Bloody Run in 

 Floyd County, where several genera and species occur in the rocks 

 of the middle Devonian. Another horizon especially rich in these 

 remains is that of the lower beds of the Upper Devonian or Hack- 

 berry group, where certain strata are crowded with them. 



A critical study of these forms as they occur in the rocks of this 

 age in Iowa, reveals much of special interest as certain of the ancient 

 conditions existing at that time are revealed. A quite exhaustive 

 study of these forms has for many years been conducted by me, and 

 the results to be published in the form of a well illustrated report on 

 them. But few if any of the forms found in the Iowa Devonian are 

 with certainty known to occur in rocks elsewhere outside this region, 

 and which adds great interest to this subject. 



Marine F'ossil Plants. 



Genus ZEARAMOSUS. N. Gen. 



Fossil sea plants or sea weeds, attaining a medium to quite 

 large size; main plant occurring in quite large rounded dense 

 bunches or clusters with short rounded heavy succulent stems more 

 or less bifurcating. From this plant springs a peculiar long and 

 heavy compound central stalk resembling somewhat in general 



