phyton. The presence of these two articulate elements in 
the Lower Devonian floras projects the history of the 
Sphenopsida much farther back than was formerly the 
case, and, since they occur on two different continents, 
the pre-Devonian history of the Sphenopsida may have 
been as long as that of the parallel groups of the Devon¬ 
ian—the Psilopsida and the Lycopsida. 
Sphondylophyton hyenioides occurs as an element of 
a typical Lower Devonian “ Psilophyton-flora.'" . The 
Beartooth Butte flora of Wyoming (4, 5) is the only 
known representative of this simple and primitive asso¬ 
ciation of plants in the western part of North America. 
Included in the flora are such forms as Hostimella sp., 
Psilophyton wyomingense Dorf, Bucheria ovata Dorf, 
and Broggeria strobiliformis Dorf. The discovery of 
Sphondylophyton hyenioides together with these Devon¬ 
ian psilopsids and other simple plants is the first evidence 
of definitely sphenopsidal elements in the “ Psilophyton - 
floras” of North America, and the second in the Lower 
Devonian of the world. 
Summary 
Sphondylophyton hyenioides Schultes & Dorf of the 
Lower Devonian of Wyoming is a plant of tufted habit, 
the axes bearing whorls of relatively large, dichotomous, 
thalloid foliar appendages. It is the first actual evidence 
of the sphenopsids in the “Psilophyton-floras” of the 
Lower Devonian of North America and the second in 
the floras of that age in the entire world. In its habit, 
the plant is much nearer an ancestral algal form than is 
any previously known sphenopsid. 
