00 PEOF. A. C. SEWARD : CONTRIBUTION TO [March 1913, 



this interesting fern. The frequent association of Hausmannia and 

 Matonidium in the Pairlight Clay (PI. XIV, fig. 3 a) bears striking 

 testimony to the fact, that the association on Mount Ophir in the 

 Malay Peninsula of the genera Dipteris and Matonia is a survival 

 at the present day in the Southern Hemisphere of a sample 

 of European Wealden and Jurassic vegetation. There can be 

 little doubt as to the very close affinity of these two geographicalh- 

 restricted existing genera to the fossil species of Hausmannia and 

 Matonidium. 



The fronds of Hausmannia pelletieri vary in size from the 

 deeply-bilobed form, 2 cm. broad, represented in PI. XIV, fig. 2 

 (thrice the natural size), to the larger and more dissected type 

 reproduced (natural size) in fig. 3 of the same plate. 



The lamina of the smaller leaf bears a close superficial resem- 

 blance to a small form of Ginkgo biloba L. or G. digitata (Brongn.): 

 in the larger fronds (as, for example, fig. 3) the lamina is divided 

 into obcuneate segments, characterized by a few strong ribs and a 

 reticulum of finer veins. The forked main ribs spread from the 

 summit of a fairly long petiole (fig. 2) ; from them numerous 

 branches are given off at right angles, and the finer veins form an 

 irregular reticulum with the ultimate branches ending blindly in 

 the polygonal areas. 



The species Hausmannia Jcohlmanni, founded by the late 

 Dr. Pdchter 1 on material from the Lower' Cretaceous strata of 

 Strohberg, in Germany, differs from H. pelletieri in the less deeply- 

 cut lamina and in the more entire margin. The smaller German 

 species, H. sewardi Bicht. 2 is distinguished by its entire and 

 obovate lamina. The frond shown in PI. % XIV, fig. 3 closely 

 resembles some forms of H. dichotoma 3 ; but in that species the 

 segments are usually narrower than in H. pelletieri, and the leaves 

 reach larger dimensions. 



Comparison may also be made with Bartholin's Lower Jurassic 

 species //. forchhammeri, 4 and with H. crenata Xath., as figured 

 by Moller 5 : both from Bornholm. The fragments described by 

 Schenk from the German Wealden as Dictyopliyllum rcemeri 6 are, 

 in all probability, correctly referred to that genus rather than to 

 Hausmannia : on the other hand, Heer's Dictyopliyllum diclcsoni ~ 

 from the Koine Beds of Greenland may be a piece of a Hausmannia 

 frond. It is also probable that some of the fragments described in 

 Part I of the British ' Wealden Flora ' as Dictyopliyllum roemeri 

 should be removed to Hausmannia • and the same statement applies 

 to a specimen figured from the Wealden of Bernissart as Protorhipis 

 roemeri. 9 



1 Eichter (06) p. 21 & pis. i, ii, v. 



2 Ibid. p. 22 & pi. i, fig. 12 ; pi. v, figs. 3-4. 



3 Seward (11) p. 657 & pi. i, figs. 14-17, 19 ; pi. ii, fig. 20. 



4 Bartholin (92) pi. xi. 



5 Moller (02) pi. v, figs. 5 & 6. 



e Schenk (71) pi. xxxi, fig. 3 & pi. xxxvi, figs. 7 «-7 b. 



7 Heer (74) pi. iii, fig. 9. 



8 Seward (00) p. 18 & pi. iii, fig. 34. 



