XXXIX] DICTYOZAMITES 547 



is generally more definitely lobed. The imbricate bases completely 

 cover the upper face of the comparatively slender rachis. The 

 longest pinna seen on an Indian frond is 6 cm. with a breadth of 

 2 cm. Some of the pinnae on magnification exhibit a finely 

 tuberculate appearance, due no doubt to the presence of papillae 

 on the epidermal cells like those on the pinnae of English and 

 Bornholm specimens. This species is recorded by Yokoyama 1 

 from Japan as D. falcatus var. distans, and a similar form, referred 

 by him to a distinct species, D. grossinervis, may be more appro- 

 priately named D. falcatus var. grossinervis 2 . The Indian type 

 occurs also in Jurassic rocks of Korea, and Halle has discovered 

 some Dictyozamites leaves in Tierra del Fuego 3 which he describes 

 as Dictyozamites sp. cf. D. falcatus : this record is of special interest 

 from a phytogeographical point of view. 



Dictyozamites Johnstrupi Nathorst. 



This species 4 , from rocks usually spoken of as Liassic but not 

 improbably Middle Jurassic in age, differs from D. falcatus in the 

 slightly more falcate form of the pinnae and in the more strongly 

 auricula te upper angle of the base of the lamina. The stomata 5 

 are confined to the lower epidermis and the strongly cuticularised 

 guard-cells frequently lie at right- angles to the course of the veins. 

 The epidermal cells have very sinuous walls (fig. 609, C) and in 

 the middle of each is a prominent papilla. 



Dictyozamites Hawelli Seward. 



This Middle Jurassic type from Marske 6 , Yorkshire, differs 

 from D. falcatus in the relatively broader segments, their straighter 

 form (fig. 609, B), and in the attachment to the rachis being 

 slightly below the middle of the pinna base. Fig. 609, A, shows 

 the base of a pinna and an oval scar similar to those on the rachis 

 of some recent Cycads (cf. fig. 387). The epidermis is like that in 

 D. Johnstrupi and as in that species the stomata are confined to 



1 Yokoyama (89) B, PL vn. fig. 10; Pis. x., xi. 2 Seward (03) p. 217. 



3 The statement made by me [Seward (II 4 ) p. 3] that Dictyozamites occurs in 

 the Falklands is incorrect. 



* Nathorst (89); Moller (03) p. 25, PL v. 



5 Nathorst (07 2 ) PL in. figs. 28. 



6 Seward (03); Thomas (13 2 ) p. 238; Thomas and Bancroft (13) p. 186, PL xix. 

 figs. 68. 



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