DESCRIPTION OF SPECIES. PP. 115 



also, belong to Schimper s section Cyatheides, of which Pe- 

 copteris arborescens is the type. 



AVhile the marked decadence of characteristic Carbonif- 

 erous forms has affected the facies of the flora of tli,e Upper 

 Barrens, a still greater change is produced by the introduc- 

 tion of new features, among which we find the first appear- 

 ance of types destined to reach their culmination in the 

 Mesozoic. We will specify only a few of these new features. 



The Neurojpterids show a Permian character in the ten- 

 dency of the middle nerve to split up, and in the approach 

 of their nervation to the Mixoneura type of the Odontop- 

 terids. In this feature, and in the great size of the rachis, 

 tliey resemble the Permian Neuropterids of the type of N. 

 Dufresnoyii Brongt. The SpJienoiyterids, in the delicacy 

 of their foliage, and the character of their lobing, differ 

 much from those of the Carboniferous, and show affinities 

 with Mesozoic forms. Sphenopteris minutisecta resembles 

 a Thyrsopteris ; S. acrocarpa, in the foliage of the sterile 

 plant, resembles this genus ; while the only fossil plant 

 known to us which has a somewhat similar fructification, 

 is the Acropteris cuneata of Schenk, found in the Rhaetic 

 of Europe. Our Equisitides elongatus, in the long linear 

 divisions of the sheath, consolidated except at the top, 

 and terminating with obtusely rounded ends, as well as in 

 the strong middle nerve which runs down the surface in the 

 middle of each leaflet, is more like the peculiar Equisetum 

 triphyllum, of Heer, from the Trias of Switzerland, than 

 any other described fossil form. Pecopteris merianiopte- 

 roides, is strikingly like Heer's Triassic genus, Merianiop- 

 teris; while Pecopteris pachypteroides, has many of the 

 features of Pachypteris. 



A very interesting feature shown in some of the forms of 

 Pecopteris, and Callipteridium, is the foreshadcAving of 

 some of the characters of the Mesozoic Pecopteridse, of 

 the type of Pecopteris Whitbyensis. In the falcate, acute 

 pinnules, the long, almost linear pinnae and the nervation, 

 we have the features of the genus Cladophlebis, as limited 

 by Saporta. 



The appearance in the Upper Barrens of Saportaea, a ge- 



