SPHENOPHYLLALES-SPIIENOPHYLLITM. 185 



gradually upward and slightly inward, while eacli joint of the main stem 

 is provided with a verticil of leaves within which the Ijranches have their 

 origin. But, although by this character of the main stem, the internodes 

 of which are much longer in proportion to their width than in other speci- 

 mens, and b}' the angle and habit of the branches this individual specimen 

 is so different from all others examined, being in effect very similar to 

 Asteroplvijllites gracilis Lx., still the characters of the leaves and branches are 

 so concordant with those in the dichotomous form that I am not at present 

 prepared to establish any separation of the two, especially in the absence 

 of additional details as to the internal organization or fruit of the latter. 



The following remarks, hoNvever, pertain entirely to the remaining 

 suite of specimens, all of which are more or less distinctly of the type of 

 fig. 1 of the plate in the Coal Flora. 



The stems of the common (dichotomous or fasciculate) type, some of 

 which are nearly 1 cm. in diameter, are usually more or less flexuous, 

 especially the smaller ones, while the delicate twigs are often sinuous and 

 plumose, the branching being irregular and not in the same plane. In fact, 

 the general aspect of the plant and the more obvious characters of the 

 stems of all ranks are so strongly similar to those of the stems and 

 branches of common Sphenophylla, such as Siohenophyllum emdrginatum 

 Brongn., that it is onl}^ after a glance at the leaves that one pauses to inquire 

 whether it belongs to some other group. The ribs are few, broad, broadly 

 rounded or flattened, and separated in the larger segments by a rounded 

 furrow. Toward the upper end of the internode each rib is somewhat 

 swollen. Confluent with the upper ends of these ribs are the slightly 

 thickened bases of the leaves, which are inclined upward as is common in 

 Spliemphyllum, _^o that just above the node, or within the verticil, the stem is 

 reduced in size. These features may be indistinctly seen in PI. L, I'ig. 3. 



In the larger and older stems the leaf traces show indistinctly as roundish 

 or transversely oval scars more or less distinctly paired according to the size 

 of the stem. In such advanced stems the leaves are so open that they are 

 seldom seen except in profile. However, in the younger portions, and 

 particularly near the ends of the branches, the leaves may often be seen at 

 a right angle to their planes, in which cases they are found to be united, 

 two by two, for a distance (sometimes nearly one-third of their length), 

 while in still other cases the pairs are more narrowly united into what is 



