112 



Both the British Museum and the Oxford Museum collections- 

 include several examples of the pinnee of Zamites. In many of 

 them the base is well shown: it has the form of a clean-cut 

 margin terminating the pinna by a curved line, which may extend 

 sufB^ciently far into the lamina to present the appearance of a semi- 

 circle. In some of the larger pinnse the base is slightly over 2 cm. 

 in breadth, and is thus greater than that of the pinnae of recent 

 Cycads. Another characteristic feature is the very gradually 

 tapered apical portion of the pinna, and, as seen in the drawing 

 (PI. XII. Fig. 5), the surface of the lamina is strongly convex in 

 its narrow part: this convexity is no doubt the result of contraction, 

 of the stout leathery pinna after death. The occurrence of pinnae 

 which exhibit identical features, varying in length from 3'5 to 

 33 cm., is an additional piece of evidence in favour of regarding 

 them as segments of large Cycadean fronds. The parallel veins are 

 clearly shown in the fragments of lamina represented in PI. XII. 

 Fig. 1, and in PI. X. Fig. 4. 



The long parallel-veined leaves figured by Zigno from Jurassic 

 rocks of Italy as Tuccites Schimperianus are probably identical 

 with the Stonesfield Slate pinnae. Other fossils comparable with 

 Zamites megaphyllus are Zamia washingtoniana^ a Potomac species- 

 described by Ward, leaves from the Lower Cretaceous of Bohemia 

 referred by Velenovsky to the genus Krannera"^ {K. mirabilis, 

 Cord.), and Schenk's species PteropJiyllum giganteum,^ from the 

 Trias Eaibl beds. One may note also a resemblance between thfr 

 Stonesfield pinnae and the long narrow leaves from the Ehaetic of 

 Tonkin identified by Zeiller as Noeggeraihiopsis Sislopi^ 



Nathorst has suggested that Phillips' species Palmozamia mega- 

 'la ( = Zamites megaphyllus) should be referred to Tuccites.^ 



V. 86. PI. X, Fig. 4. 



A small piece of a broad pinna 16 cm. long and 4 cm. broad. 

 The lamina is traversed by numerous parallel veins between which. 



' Ward (95), pi. ii. fig. 6. 

 ' VelenoTsky (85), pis. i.-iii. 

 ' Schenk (66), pi. ii. 

 ^ Zeiller (02), pi. xl. 

 5 Nathorst (80), p. 79. 



