THE JURASSIC FLORA OF SUTHERLAND. 669 



recognisable by its large pinnules, broadest at the base and with denticulate margins, 

 also by the ultimate segments being less crowded than in the similar type C. nebbensis, 

 and by the single dichotomy of the secondary veins. It is very doubtful whether the 

 presence or absence of marginal teeth is a feature of importance. Pinnse are often met 

 with in Jurassic rocks bearing entire pinnules indistinguishable from those of C. denticu- 

 lata except by the absence of denticulations. The specimen reproduced in photo. 9, 

 PL VI., is a case in point : the pinnules are apparently entire, but in other respects 

 identical with those of the typical C. denticulata. A denticulate margin is seen in 

 the portion of a pinnule represented in fig. 38, PL II., and in the pinnules enlarged in 

 fig. 31. It is not easy in the case of apical portions of fronds to separate C. denticulata 

 from Todites Williamsoni (Brongn.), but as a rule the shorter and relatively broader 

 segments and their more crowded arrangement constitute well-defined characteristics 

 of the latter species. Photo. 9, PL VI., shows the falcate form of the linear pinnules 

 with broad bases, the alternate pinnse, and the single dichotomy of the lateral veins. 

 In some of the Culgower specimens the pinnules reach a length of 2 '5 cm. and a 

 breadth of 7 mm. The rachis is narrower than in Todites Williamsoni. The degree 

 of inclination of the segments to the pinna axis is by no means constant ; the lower 

 edge is usually strongly curved upwards, as in photo. 9, and a still greater inclination 

 is seen in figs. 35, 36, PL II. The specimen represented in photo. 8, PL VI., has 

 shorter pinnules than those seen in many examples, but the venation appears to 

 conform to the type. A smaller apical piece is shown on fig. 34, PL II. : fig. 32, 

 PL II., shows the characteristic venation. With some hesitation I refer the specimens 

 represented in photo. 29, PL VIII. , and in fig. 33, PL II., to this species, though the 

 straighter and narrower form of the pinnules may be a specific character. In the case 

 of the impression shown in photo. 29 the preservation is far from good, and the 

 narrower form may be partially due to this fact. The imperfect fragment represented 

 in fig. 56, PL IV., is apparently characterised by a lobing of the pinnules and may 

 belong to a distinct type or even to another genus, e.g. Thinnfeldia : the preservation 

 is, however, too imperfect for satisfactory determination. Photo. 29, PL VIII., bears 

 a very close resemblance to specimens described by Velenovsky # as Pteris frigida 

 Heer from Lower Cretaceous rocks in Bohemia, and to the Indian Jurassic fern figured 

 by Feistmantel as Alethopteris Medlicottiana Old.t 



Cladophlebis denticulata had a very wide geographical range in the Jurassic period ; 

 it closely resembles C. nebbensis Brongn. as represented by such specimens as those 

 figured by Nathorst J from the Rheetic beds of Scania, and by Zeiller § and Yokoyama || 

 from the Rhsetic of Tonkin and Japan respectively. The Lower Cretaceous species 

 C. Albertsi (Dunk.) from the Wealden of Germany and England,H also C. frigida 

 (Heer) from Greenland * # and elsewhere, are similar forms of the genus. The fronds 

 described by Hartz from Lower Jurassic (or Rhsetic) strata in Greenland as 



* Velenovsky (85), pi. iv. t Feistmantel (77), pi. i. { Nathorst (78). 



§ Zeiller (03). || Yokoyama (05). 1 Seward (94). ** Heer (82). 



