THE JURASSIC FLORA OF SUTHERLAND. 697 



Nilssonia brevis Brongniart. (PI. IX. photo. 37.) 

 1825. Brongniart, Ann. Set. Nat., tome iv. p. 218, pi. xii. figs. 4, 5. 

 The specimen represented in photo. 37 consists of a portion of a frond with a median 

 ridge and a lamina characterised by transverse folds which divide it into approximately 

 equal strips. In the reverse piece of the same impression the axis is represented by a 

 groove and the edge of the lamina is seen to be entire, but the transverse folds tend to 

 converge slightly towards the margin. There is no definite venation recognisable, but 

 in places one can detect some striations at right angles to the central axis. This fossil 

 bears a close resemblance to some of the smaller impressions of Nilssonia brevis recently 

 figured by Nathorst in his important monograph of the genus. # N. brevis was founded 

 by Brongniart on material from the Hor sandstone of Sweden of Liassic age. 

 Nathorst shows clearly how the upper and lower surfaces of this type differ from one 

 another, not only in the presence of a prominent rachis on the lower face, but in the 

 appearance of the lamina ; seen from above, the lamina is divided by grooves or folds 

 into transverse, smooth, and slightly convex strips, while on the lower face the regions 

 between the folds are traversed by several subordinate ridges and grooves. The exposed 

 face of the Culgower specimen is probably the upper, the lamina being destroyed along 

 the median line. The upper part of the specimen reproduced in Nathorst's fig. 11. 

 PI. II., agrees very closely with the impression shown in photo. 37. Among other 

 figures given by Nathorst which exhibit the most striking likeness to the Sutherland 

 specimen are the following: pi. i. fig. 14; pi. ii. figs. 14, 16, 17; pi. vi. fig. 5, etc. 

 This species is said to occur very rarely in the Rhsetic of Scania and is recorded from 

 several localities in Germany. Nilssonia brevis, as represented by the Culgower 

 specimen, may be compared with Pterophyllum contiguum Schenk f as figured by 

 Zeiller from the Rhastic of Tonkin. 



Nilssonia cf. Nilssonia compta (Phillips). (PI. V. figs. 78, 81.) 



The fragment seen in fig. 78 shows a broad rachis bearing portions of broad truncated 

 segments transversed by numerous fine veins about '5 mm. apart. In the pinna repre- 

 sented in fig. 81 the veins are more prominent and rather farther apart. These 

 specimens, though possibly not specifically identical, closely resemble the common 

 Jurassic type Nilssonia compta ; ]. they agree also, but to a less extent, with the 

 Wealden species Nilssonia Schaumburgensis (Dunk.) as figured by Dunker§ and by 

 Schenk. || 



Nilssonia mediana (Leckenby ex Bean MS.). (PI. VII. photo. 13 ; text-fig. 13, C.) 



1864. Pterophyllum mediauaum, Leckenby, Quart. Journ. Geol. Soc. London, vol. vi. p. 77, pi. viii. fig. 3. 



The imperfect specimen reproduced in photo. 13 is characterised by the long and 



relatively narrow pinnae, the least incomplete of which has a length of 6 cm. and a blunt 



* Nathorst (09), p. 12, pis. i., ii., v. -viii. t Zeiller (03), pi. xlviii. 



% Seward (00), p. 223, pi. iv. fig. 5. § Dunker (46), pi. vi. || Schenk (71), pi. xxxiii. 



