224 NILSSONIA. 



1887. Cf. Nilssonia potymorpha, Schenk, Foss. Pflanz. Albourskette, p. 7 r 



pi. i. fig. 3 ; pi. v. fig. 22. 

 ? N. compta, ibid. pi. viii. fig. 47. 

 1892. Nilssonia compta, Fox-Strangways, Tab. Foss. p. 139. 



Frond broadly linear, varying considerably in size and in the 

 depth and number of the segments. The lamina is dissected up to 

 the central midrib or rachis into truncate segments of unequal 

 breadth, traversed by several parallel veins both simple and 1 

 forked ; the lamina is continuous over the rachis of the frond, and 

 the segments are not laterally attached as in Pterophyllum. 



Brongniart includes in his Prodrome, under the name Pterophyllum 

 Williamsonis, a species from the Lower Oolite in the list of examples 

 of Pterophyllum, but in the Tableau this name occurs as a synonym 

 of Nilssonia compta. Phillips' figure of this species in the Geology 

 of the Yorkshire Coast represents a portion of a frond one-half 

 natural size. An earlier drawing given by Young & Bird of 

 A specimen which is now in the Whitby Museum (No. 2381) 

 illustrates somewhat crudely the characteristic features of the same 

 type of leaf. 



Nilssonia compta is one of the most abundant species in the 

 Inferior Oolite flora, and is usually represented by several 

 specimens in museum collections. Without attempting a com- 

 parative account of the various fossils of Mesozoic age which agree 

 more or less closely with Phillips' species, attention may be drawn 

 to the large leaves figured by Fontaine from the Potomac plant- 

 beds under the name Platypterigium densinerve. 1 An examination 

 of a few specimens of this species in the Washington Geological 

 Museum led me to regard the plant as probably a Nilssonia. 



The large and broad fronds from the Rajmahal Hills of India, 

 figured by Oldham & Morris 2 and by Feistmantel 3 as Pterophyllum 

 princeps, bear a close resemblance to the largest examples of 

 Nilssonia compta ; it is not clear from the illustrations if the 

 segments of the lamina are laterally attached as in Pterophyllum, 

 or if the median portion of the frond is incomplete and presents 

 a deceptive resemblance to that genus. In specimens of Nilssonia 

 compta, one occasionally sees the rachis represented by a fairly 



1 Fontaine (89), pi. xxx. fig. 8 ; pis. xxxi.-xxxv. 



2 Oldham & Morris (63), pis. x.-xiii. 



3 Feistmantel (77), pi. xlvii. 



