THE JURASSIC FLORA OF SUTHERLAND. 659 



Zeiller # has assigned to Andrae's species specimens from the Steierdorf beds 

 which differ from the type in the presence of a median sinus, and in this respect agree 

 with Kichter's species H. Kohlmanni : the latter author has made Zeiller's specimens 

 the type of a new species, H. Zeilleri. In the two specimens from Culgower shown in 

 text-fig. 3 and in fig. 6, PI. VI., the edge of the lamina is torn, and it is difficult to 

 distinguish between true lobing and the result of tearing. The lamina probably 

 reached a length of 12 cm. from the top of the petiole, and a breadth of 16 cm. In 

 some places there are indications of finer veins at right angles to the main ribs. The 

 typical Hausmannia venation is shown in the fragment represented in text-fig. 2, which 

 may belong to this species, and in the enlarged portion of a leaf shown in fig. 21, PL II. 

 In Kichter's species H. Kohlmanni the fronds differ but little from those of H. Buchii, 

 but the lamina appears to be always characterised by a distinct median sinus. Some of 



Text- Fig. 3. — Hausmannia Buchii (And.) From a block lent by the Cambridge University Press.* (Nat. size.) 



* Seward (10), p. 393, fig. 289. 



the larger specimens figured by Bartholin t and by MollerJ; from the Lias of 

 Bornholm as H. Forchammeri Barth. are hardly distinguishable from H. Buchii, 

 though in the Bornholm type there is evidence of considerable variation in the degree 

 of dissection of the lamina. 



General Remarks on the two species Hausmannia dichotoma Dunk, and 



H. Buchii (And.). 

 Though it would be rash and perhaps incorrect to unite under one specific term 

 fronds differing as much from one another as those represented in fig. 14, PL I., and 

 photo. 6, PL VI., it is admissible to suggest the possibility that Hausmannia may 

 have been a heterophyllous epiphytic fern like Platy cerium. As in that tropical 

 epiphyte we find long and deeply lobed leaves like those of II. dichotoma, acting as 

 carbon-assimilating organs, and another form of frond, the so-called mantle-leaf, 

 orbicular and entire, adapted to the collection of debris ; so in the Jurassic species 

 there may have been a similar division of labour in the foliar organs. This somewhat 



* Zeiller (97), pi. xxi. figs. 1-5, p. 51. + Bartholin (92), pis. xi., xii. % Moller (02), pis. iv., v. 



TRANS. ROY. SOC. EDIN., VOL. XLVII. PART IV. (NO. 23). 98 



