Maryland Geological Survey 371 



genus, one other being from the Ehcetic, and the balance from somewhat 

 later, Jurassic horizons. Braun considered these forms referable to the 

 ferns and compares them with the Marsiliaceae. In this he was followed 

 by Schimper (1869) ; and Schenk (1871), who include them in the family 

 Neuropteridse. Both authors, however, subsequently placed the genus 

 in the Gymnospermas (In Zittel's Handbuch, 1890), where they are 

 commonly considered to belong at the present time as members of the 

 order Ginkgoales (Pontonie, 1889, Saporta, 1879, Solms-Laubach, 1891, 

 Zeiller, 1900, etc.). Certainly the sporophylls and fruits described by 

 Schenk, Heer and Leuthardt, in some of the older Mesozoic forms are 

 conclusive evidence of their gymnospermous nature, especially when 

 considered in connection with the multipartite and undoubted true Gink- 

 goes of the later Jurassic and the well-known tendency of the leaves of 

 the modern Ginkgo in localized situations (seedlings, shoots, and grafts), 

 to revert to a very Baiera-like form. 



Seward^ states that it is not improbable that some of the species of 

 Baiera are best compared with certain recent ferns such as Actinopteris 

 radiata Link and Schizcea dichotoma Sw., or Schizcea elegans Sw., and in 

 this connection (Wealden FL, pt. ii, 1895, p. 5, pi. xiii, figs. 1, 3), he 

 points out the considerable resemblance to Baiera shown by the fronds of 

 Macrozamia heteromera Moore var. Narrabri and var. glauca, Australian 

 cyeads with peculiar repeatedly forked pinnae. It is believed that such 

 resemblances are purely fortuitous and in no way discredit the evidence 

 furnished by fossil foliage, although it is not overlooked that some of 

 the species referred to Baiera may not be related to those forms of 

 Baiera whose botanical relations have been demonstrated. In all the 

 species the leaves are repeatedly and dichotomously inciso-partite and 

 are distinguished from Ginkgo by the shortness of the petiole, and by 

 the greatly elongated and narrow linear segments in the ultimate 

 divisions of which there is no further forking of the veins. In habit, 

 the leaves appear to have been borne in tufts at or near the summit of 

 short axillary branches, much as in the modem Ginkgo, but this habit 



^ Jurassic Fl., pt. i, 1900, p. 262. 



