MARYLAND GEOLOGICAL SURVEY 803 



Description. Leafy twigs, apparently deciduous in habit, bifacial, phyl- 

 loclad-like, consisting of cyclically-arranged leaves. Along the main 

 axis on each flat face of the branch these leaves are relatively and closely 

 appressed, with a narrow base and a broad semicircular apex. The cor- 

 responding lateral pairs of leaves are thin and pointed and transversely 

 compressed. In the axis of each of these marginal leaves is a reduced 

 branch flattened in the same plane as the main branch, so that the whole 

 arrangement is strictly opposite and distichous. These reduced lateral 

 branches have leaves of the same character and arrangement as those of 

 the main branch. The bifacial leaves are, however, somewhat smaller 

 and blunter and the marginal leaves are broader and less acute. They 

 become rapidly smaller distad, it usually requiring not more than five or 

 six pairs to complete the blunt lateral reduced twigs. The main vascular 

 arrangement is strictly opposite and distichous. These reduced lateral 

 branches. The leaves fail to show any veins. The texture was apparently 

 coriaceous but obviously thin in the majority of specimens. No structural 

 material or indications of fruits or fruiting characters have been discov- 

 ered. This species, formerly confused with Moriconia cyclotoxon of Debey 

 and Ettingshausen, differs from the latter, which is the type and only other 

 known species of the genus, in being more phylloclad-like and strictly 

 comparable to a cupressineous genus like Libocedrus. It is also much 

 larger (about 100 per cent) than the type of the genus, the lateral twigs 

 are more reduced and the main axis is invariably leafy. It differs also in 

 its geological range, the two species not being anywhere contemporaneous 

 in America, although the type in Europe extends as high as the later larger 

 form of America. 



Superficially these remains closely resemble fragments of fern fronds; 

 in fact, Debey, the original discoverer, always insisted that they were 

 ferns, and Heer described the earliest collected and poorly preserved 

 remains from Greenland as a species of Pecopteris. There can be no 

 doubt, however, of their gymnospermous nature. For stratigraphic pur- 

 poses they are one of the most characteristic fossil plants known, since the 

 geometrically arranged outline of the leaves is recognizable with certainty 

 in the smallest fragment. 



