676 PROFESSOR A. C. SEWARD ON 



with Moller's Bornholm species described as Cycadopteris heterophylla* Zig., a 

 species which he regards as identical with Lomatopteris jurensis of Kurr. It may be 

 compared also with Pecopteris Schonleiniani Brongn. described by Szajnocha t from 

 the Argentine Rhsetic, and with Pachypteris ovata Brongn. figured by Saporta.J 



The pinnules shown in the photo. 21, PI. VI L, are of the T. rhomboidalis type, but 

 are much more highly inclined to the pinna axis. The specimen represented in fig. 72, 

 PI. IV., though possibly a distinct species, is included under T. rhomboidalis because 

 of its close resemblance to the smaller fragment shown in fig. 70 A, PL IV., which forms 

 a connecting link with the larger example represented in fig. 66. Fig. 72 presents a 

 close agreement with Lomatopteris Schimperi as figured by Salfeld § from the Jurassic 

 of Germany, a species founded by Schenk on Wealden fronds ; the resemblance 

 probably does not amount to specific identity. 



Rhsetic examples of Thinnfeldia from South America (Cacheuta), for which I am 

 indebted to Dr Kurtz, appear to be identical with the larger Culgower specimens ; 

 similarly the Rhsetic specimens described by Schenk from Franconia, and by myself 

 from South Africa as T. rhomboidalis, cannot be distinguished satisfactorily from 

 the Scotch examples. It would seem that this type of Thinnfeldia had a wide range 

 in time, persisting from the Rhsetic || and Liassic II to the latter part of the Jurassic 

 era. A very similar type is represented by T. indica Feist.*'* recorded from India, 

 Australia, and elsewhere. 



In the case of small specimens such as that shown in fig. 82, PL V., it is practically 

 impossible to decide between Dichopteris or Pachypteris and Thinnfeldia as the more 

 appropriate generic name ; the specimens referred to bear a close resemblance to the 

 fragment figured from the English Wealden as Dichopteris sp.,tt and may be compared 

 also with a Lower Cretaceous species described by Kerner H from the island of Lesina. 



Thinnfeldia sp. (Text-fig. 7, A-C.) 



Text-fig. 7, A, shows the outline of a small piece of a Thinnfeldia leaf detached from 

 the shale as a cuticular film and treated with nitric acid and chlorate of potash. The 

 specimen, 1 "5 cm. long, agrees in habit and may be specifically identical .with that 

 shown in fig. 72, PI. IV. It may be compared also with Pachypteris brevipinnata 

 Feist, from Jurassic beds of India. §§ The broad rachis is covered with a layer of 

 elongated cells as shown in fig. 7, C, and cells of the same type occur over the central 

 veins of each leaflet. The cell walls are thick and, at first sight, appear to be slightly 

 sinuous, but this is no doubt due to an unequal swelling of the membrane. The epi- 

 dermis of the pinnules, with the exception of a median strip, consists of polygonal cells 

 with straight walls. There are no indications of any lateral veins. The stomata, 



* M6LLER (02), pi. ii. t Szajnocha (88), pi. xxvii. J Saporta (73), pi. xlvi. 



§ Salfeld (09), pi. vi. || Schenk (67), pi. xvii. IT Seward (04), pi. iv. 



** Feistmantel (80), pis. xxxix., xl. tt Seward (94), pi. xii. fig. 6. 



\l Kerner (95). §§ Feistmantel (80), pis. iii., iv. 



