EOTTOEBIA. 79 



The small piece flgurei? by Trautschold as Sphenopteris AuerlacM, 

 Traut., from the Klin Sandstone seems to be identical with some 

 forms of Ruffordia QUpperti, as first suggested by Sohenk.' Schenk 

 compares Ruffordia OSpperti 'with. Sphenopteris Stenstrvpi, Hr., and 

 S. Hinslopi, Old. ; his figures represent imperfect pieces of pinnae. 



There is no mention of this species by Fontaine in his " Potomac 

 Flora ; " one of his species, S. aorodentata,^ founded on a very 

 small fragment, seems to be almost identical with the broadest 

 forms of our English species, and especially with such as I propose 

 to consider as Ruffordia GUpperti, var. laiifoUa. From the small 

 piece figured by Fontaine it is impossible to form any idea of the 

 habit of the fern ; the character of the pinna represented by him 

 in fig. 4, pi. xxxiv. seems to be very much the same as that of 

 Thyrsopteris Irevipennis, Font., represented in the same plate, 

 figs. 3 and 3« ; in the former the pinnules are dentate, in the 

 latter entire. 



In addition to the specimens figured by Nathorst from Japan 

 as S. Gbpperti, those fragments described and figured by Toko- 

 yama as Thyrsopteris Kagensis, Tok.,^ should be compared with the 

 present species ; there is no adequate reason for referring them to 

 the genus Thyrsopteris. 



Repeated examinations and comparisons of a large number of 

 specimens in the Museum Collection, have led me to regard Ruffordia 

 Oopperti as a species of which the vegetative parts are extremely 

 variable, and to a much greater extent than the figures hitherto 

 published would lead us to expect. Th* task of determining, or 

 attempting to determine, what limits to assign to this species has 

 been attended with considerable difficulty, and the conclusion 

 arrived at is one which will doubtless suggest that two or more 

 specifically distinct forms have been included under one name. 

 My first inspection of the material favoured the view of two or 

 tliree species or, at any rate, varieties ; hut a more detailed 

 examination forced me to the conclusion that I was dealing with 

 a number of specimens, which could be arranged in a regular and 

 gradually varying series, with a marked difierenoe in form 

 between the extreme types. 



' Palseontographica, vol. six. p. 261. 



' Potomac Flora, p. 90, pi. ixxiv. fig. 4. 



' Joum. Coll. Sci. Japan, toI. ill. 1890, p. 23, pi. i. figs. 6 and 6b. 



