88 pkoe. a. c. seward : contribution to [March 1 91 3, 



(Natural History Museum). The fact that in the Jurassic species 

 Sagenopteris phillipsi (Brongn.) there is clear evidence of con- 

 siderable variation in the size of the leaflets and in the extent and 

 distinctness of the midrib, lends support to the view that a similar 

 variability characterizes the Wealden type, of which there is less 

 available material. In all probability, the larger leaflet shown in 

 PI. XI, fig. 3, which reached, when complete, a length of 7 cm. 

 and has a much more distinct midrib than the shorter leaflets, 

 is not specifically distinct from the example represented in fig. 5 

 of the same plate. The long and narrow meshes formed by the 

 anastomosing veins are approximately 0'7 mm. in breadth. 



The close agreement between S. mantelli and S. phillipsi is such 

 as to render impossible a satisfactory separation in all cases ; but, 

 having regard to the average form of the leaflets, it would seem 

 that in S. mantelli the lamina is usually shorter and broader 

 than in the older form. A comparison of some specimens, recently 

 described from the Kimmeridge Beds of Sutherland x as S. phillipsi, 

 with that represented in PI. XI, fig. 3 illustrates the difficulty of 

 accurate determination. 



The specimens described by Fontaine and Berry 2 as S. elliptica 

 from the Potomac Group, and compared by the latter with S. man- 

 telli, agree very closely with the leaflet shown in fig. 3. The 

 examples figured by Fontaine as S. elliptica, 3 from the Shasta 

 Formation of California, are in all probability referable to S. man- 

 telli. The imperfect fossils from South-Eastern Scania, probably 

 of Middle Liassic age, compared by Dr. Halle i with S. mantelli, 

 are too incomplete to be referred to that type with any degree of 

 certainty. 



Sagenopteris acutifolia Sew. (PI. XI, fig. 4.) 

 (Ecclesbourne, Bufford Coll.) 

 1895. A. C. Seward, ' Wealden Flora ' pt. 2, p. 225. 



The narrow leaflet represented in fig. 4 is characterized by a 

 distinct midrib ; the lateral veins are obscure, but there are indi- 

 cations of anastomosis. This specimen is similar in size and shape 

 to one from the Hastings neighbourhood originally described as 

 Phyllopteris acutifolia, 3 and afterwards, as the result of a re- 

 examination of the impression, referred to the genus Sagenopteris. 



These narrow leaflets resemble the smaller forms of S. undulata 

 Xath., 6 and are very similar to some of the specimens from Suther- 

 land included in S. phillipsi' 1 It is by no means unlikely that the 

 leaflet reproduced in PI. XI, fig. 4 is specifically identical with 

 the large examples shown in figs. 3 & 5 of the same plate. 



1 Seward (11) pi. i, fig. 1. 



2 Berry (11 s ) pp. 287-89. 



3 Fontaine in Ward (05) p. 236 & pi. lxv, figs. 39-40. 

 * Halle (10) p. 8 & pi. i, figs. 18-21. 



5 Seward (94) p. 143 & pi. ix, fig. 6. 



Halle (10) pi. i, fig. 3. 



7 Seward (11) p. 656 & pi. i, fig. 4. 



