XXXIV] COMPARISON 323 



alliance was very wide. In his Hooker Lecture, p, 238, Seward remarks: 

 "There can be no doubt that the genera Mato/iza and Dipteris belong to 

 a section of the Filicales which in former days rivalled in its geographical 

 range the cosmopolitan Bracken-Fern of to-day: their present restricted 

 range is not an indication of relatively recent origin (p. 233).... The problem 

 of the original home of the Dipteris- Matonia stock is not easy of solution.... 

 By the Rhaetic period they were thoroughly established in the Tonkin 

 region, also in Germany and Scania.... There is no good reason to suppose 

 that this alliance was more widely represented in Tertiary floras than it is 

 at the present day." 



A further question may be the relation of Matonia to Dipteris. The 

 similarities are so strong that a general relationship must be admitted. But 

 Matonia stands apart both in stelar structure and in the sorus. The former 

 is in advance of that of Dipteris in complexity, and size alone will not explain 

 the difference, as is proved by comparison of Vol. I, Fig. 149, 2, 3. On the 

 other hand, the sorus of Matonia appears to be conservative in respect of 

 the uniseriate arrangement of the few large sporangia, though specialised in 

 respect of the indusium, and the low spore-output. In view of the low 

 spore-counts of the modern Dipterids, and the high counts of the Rhaetic 

 Dictyophylluvi exile, it would appear more desirable than ever to know the 

 spore-output for Laccopteris and Matonidiuni. Pending such data Matonia 

 may be held as a very ancient type, related on the one hand to the Gleicheni- 

 aceae, on the other to the Dipteridaceae. It is difficult to place the two 

 genera as terms of a sequence. The probability seems to be that they 

 represent independent lines of specialisation from a stock related to the 

 Gleicheniaceae. 



DIPTERIDACEAE 



(Aspidieae-Dipteridinae of Diels) 



Genus I. Dipteris Reinwards, 1824 ,. 6 species 



IHausmannia Dunker, 1846. 

 Mesozoic J Dictyophylluvi Lindley and Hutton, 1834. 

 Fossils. I Thawnatopteris Goeppert, 1841. 



\Clathropteris Brongniart, 1825. 



577 



BIBLIOGRAPHY FOR CHAPTER XXXIV 



Seward & Dale. Dipteris. Phil. Trans. Vol. 194, p. 4S7, i9oi> where references 

 to fossils are fully given. 



578. Diels. Natiirl. Pflanzenfam. i, 4, p. 202. 1902. 



579. Nathorst. Ueber Dictyop/iyl/niii und Cainptoptcris. K. Svensk. Vetenkaps-Akad. 

 Hand. Bd. xli, No. 5. 1906 



