VESPERTINE FLOKA. PP. 7 



More rarely we find a Neuroi3teris allied to N. flexuosa, 

 but, if not identical with it, a plant allied to Dawson's 

 Cyclopteris valida ; Cardiopteris I'rondosa, Schimp. and 

 other plants. 



The localities yielding the most abundant plants are Lewis 

 Tunnel near the White Sulphur Springs ; the Dora Coal 

 Field in Augusta Co. Va. ; and the coal beds of Montgom- 

 ery Co. Va. These are points whose extreme distance apart 

 is more than 100 miles. The Lewis Tunnel locality yields 

 the greatest variety of plants. 



The plants which especially characterize the group are 

 the Lepidodendra, the Archaeopterids, and the Triphyllop- 

 terids. 



The Triphyllopterids form two types. The first has the 

 lobes less deeply cut, but broad and obtuse, like Meek's 

 Cyclopteris Virginiana, or Dawson's CycloiDteris valida. 

 The second type, has narrow, deep, and pointed lobes, like 

 Meek' s Cyclopteris Lescuriana. There are probably several 

 new species of each kind ; but in the case of these plants, 

 and of the Archaeopterids, the transition from one form to 

 another is so gradual that a large amount of material is 

 needed to establish new species. 



The Archaeopterids also show two types. That which 

 is most abundant in species and individuals has narrow and 

 small pinnules, like Dawson's Cyclopteris Jacksoni. The 

 second type has broader and more flabellate leaflets, like 

 the Noeggerathia obtusa of Lesquereux. 



There is ax^parently a transition, on the one hand througli 

 the type of Archaeopteris Jacksoni into the Triphyllop- 

 terid form, with broad obtuse lobes, and on the other hand 

 through the type of Archaeopteris obtusa into the form of 

 Cardiopteris. 



Indeed all these plants, as well as the broad leaved Sphe- 

 nopterids of the lower coals, such as Sphenopteris macilenta, 

 have the facies of Archaeopteris. 



Besides these positive features, there is a negative one, 

 which, of course, so long as the collections are :ipeagre, can- 

 not possess much weight. 



No Pecopterids, Sphenopterids, Neuropterids (with one 



