CHARACTERISTICS OF ALLEGHENY FLORAS 155 



Name. Locality. 



Sigillaria camptoisenia Wood R. , Hor. 



Cordaites sp 



Rhabdocarpos (Pachytesta) cf. mansfieldi Lx... . Hor. 



GENERAL CHARACTERISTICS OF THE ALLEGHENY FLORAS 



As compared with the floras of the Pottsville formation, the floras of 

 the Allegheny series are characterized by a marked difference in the fern 

 species, the Annularis and the Sphenophyllese. Of most practical im- 

 portance, however, are Neuropteris ovata, N. scheuchzeri, and Sphenophyllum 

 emarginatum. In fact, these species in typical forms are practically om- 

 nipresent in the Allegheny series, and it is seldom that one of these is 

 lacking even in small and hastily made collections. Neuropteris scheuch- 

 zeri, in the ordinary form described by Professor Lesquereux as N. hirsula, 

 is usually most abundant. Annularia stellata and A. sphenophylloides are 

 nearly always present in any considerable quantity of material, even at 

 so low a level as the roof of the Brookville coal. 



Of the Sphenopterids the most common of the typical Allegheny 

 species are Sphenopteris mixta, S. pinnatifida, S. hymenophylloides, as iden- 

 tified by Professor Lesquereux, S. pseadomurrayana, S. chxrophylloides, and 

 S. brittsii. The more common species of Pseudopecopteris are P. obtusiloba 

 and P. squamosa. The latter is generally represented in the lower ter- 

 ranes by the small form described as Sphenopteris squamosa, which in later 

 beds passes into the form known as Pseudopecopteris anceps Lx., or Sphen- 

 opteris neuropteroides Boul. The characteristic types of Mariopteris are 

 those belonging to the ovata-cordata group, represented by Mariopteris 

 sillimanni. Mariopteris nervosa, or M. muricata var. nervosa, is typically 

 common in the Allegheny series, though it occurs also in the uppermost 

 beds of the Pottsville formation. Mariopteris newberryi appears to be 

 characteristic of the Kittanning group. 



A conspicuous feature in the Allegheny floras is the development of 

 the Pecopterids. The genus Pecopteris, which, as P. scrridata Hartt, makes 

 its appearance in the Upper (Sewell division) Pottsville of the Appa- 

 lachian trough and which seems to be represented by but one or two 

 other small species or forms of the villous group in the topmost beds of 

 the Pottsville, is present as P. dentata and the species always doubtfully 

 identified by Professor Lesquereux as P. villosa Brongn., or P. vestita in 

 the lower beds of the Allegheny series. Very soon, however, we find 

 representatives of the Goniopteroid group, such as P. unita and P. emar- 

 ginata, as well as the larger villous types of the genus, while in the Free- 

 port group the large Neuropteroid forms, such as P. polymorphs and P. 

 pteroides, are added to the slightly earlier P, oreopteridia and P, miltoni. 



