FLOKA OF TllK KOOIAMK FOK.MATION. 2i>5 



the i-achis of llic peiuiltiinate pinna, is constantly, in these specimens also, 

 ahnoi'nial in size and shape, liein<!; of the same chai'acter as in the (Jreat 

 I'alls foi-ms. This is a constant and characteristic feature. The noiinal 

 ())• common |)iiuniles also are essentially the same in char.actei' as those 

 from (ireat I'alls, hut are fienerally somewhat lai'fier. 'i"he size of the 

 normal pinnules on some of tlie (ieyser plants indicates a fei'ii consideraljly 

 lai-ii'er than the form most commonly occuri'in<>;, and Iheii- shape is som(>- 

 what different. But these larir;ei' pinnules are connected in shape and size 

 by ti'ansition forms with the more conunon ones in such way as to forbid 

 a sejKiration even as a variety. 



This fern, in the shape of its {)innules .and in its nei'vation, sti'onglv 

 reminds one of the Acrostichites forms seen in the flora of the Older 

 Mesozoic- of Virginia. As, howevei-, no fructification has been found on 

 any of the specimens, it must be placed in the group of Cladophlebis, 

 which is based on nervation. It is ti'ue th.at tliis type of n(>i'vation depai'ts 

 somewhat from the common types of Cladophlebis, but not enough to 

 pi-event the placing of tlie i)lant in tli;it comprehensive genus. In con- 

 sequence of the more complete and numerous specimens now found, the 

 character of the species must be corrected to read as follows: 



Fronds at least tripinnate; primary rachis slender: secondai-y jjinna' 

 alternate, very remotely placed, slender and propoitionally (luite long and 

 narrow; pinnules, other than the inferior basal ones, of two kinds, thos(^ 

 that occin- most commonly, which we may call the noi-mal ones, and those 

 less common, wdiich, for distinction, may be called abnormal. The norm.nl 

 pinnules are very small, mostly 2 mm. long and about as witle at their 

 bases. They are generally remotely placed and are united at base, so as to 

 form a very narrow wing on the rachis. In shape they are subrhombic to 

 suborbicular and very obtuse at their tips, or even rotundate there. The 

 longer ones are subfalcate, and all are united to the rachis by the whole of 

 a much widened base. The basal inferior pinnules of th(^ ultimate pinna) 

 carrying these, normal pinnules are much larger than the latter, and are 

 mostly flabellately 3-lol)ed, the lobes l)eing shallow, more or less rounded 

 and obtuse. The nervation of the normal iiimiules is .strong l)ut not vei'v 

 sharply defiiuxl. It consists of a nerve bundle, which dep.nrts from the 

 rachis of the ultimate pinna much nearer the inferior then the su])erior 

 margin of the pinnule, so as to divide it into two \eiy uneiiu.-d paits. 



