242 ME. HAMSHAW THOMAS ON THE EOSSIL ELOEA OF [June I9I3, 



veins — three per millimetre, the entire or irregularly-lobed margin 

 and the narrow midrib, together with the groove on the upper side. 

 In some of the specimens figured by Heer the lamina is broader and 

 the veins probably stronger than in the Gristhorpe forms, but their 

 agreement with the Marske specimens is complete. It therefore 

 appears to me that the name tenuinervis must be dropped, and that 

 of orientalis substituted in its place in the lists of Yorkshire 

 Jurassic plants. 



Specimens referable to the same species have been recorded by 

 Prof. Seward from Sutherland, and he again expresses the opinion 

 that these are identical with examples from Yorkshire determined 

 by Prof. Xathorst as tenuinervis. Among the Jurassic plants from 

 Kamenka in Southern Russia 1 I found examples which were almost 

 identical Avith the larger Marske forms, but had an undivided 

 margin. The species has also been recorded from Korea by Yabe, 

 from Oregon by Fontaine, from Japan by Yokoyama and Xathorst, 

 and from Spitsbergen by the last-named writer. The species 

 named by Heer Nilssonia jcihnstrwpi is probably also very closely 

 allied. 



A specimen of this species showing some structural features has 

 recently been described by Dr. Marie Stopes. 2 



PSEUDOCTENIS LANEI, Sp. UOV. (PI. XXIV, fig. 4 & PI. XXVI.) 



Prof. Seward, in his paper on the Jurassic Flora of Sutherland, 

 has instituted the new genus Pseudoctenis for fronds which have 

 an outline similar to that seen in Ctenis, but usually lack the 

 anastomosing veins of that form. He describes and figures several 

 specimens with linear-lanceolate pinnae, attached at a somewhat 

 acute angle to the rachis. 3 These bear considerable resemblance 

 to the form usually included in the genus Zamites, but are marked 

 off by their obviously decurrent lower margins or pinnae-bases. 

 The collections here described contain several specimens which 

 resemble the Sutherland forms, and may be referred to the 

 genus Pseudoctenis (see PL XXIV, fig. 4). They may be 

 described as follows : — Rachis 3 to S mm. broad, and marked 

 with faint longitudinal striations. The pinnae appear to arise 

 laterally from it at an angle of about 45° ; they may reach a 

 length of 10 cm. and a breadth of 9 mm. : they are linear 

 or linear danceolate in shape, becoming shorter and narrower 

 towards the apex of the frond. The margins are entire, the apex 

 acuminate, while the pinnae taper slightly also towards the base. 

 The lower (abaxial) margin is markedly decurrent at the base. 

 The lamina is traversed by numerous fine parallel veins, ten of 

 which occupy a width of about 6 mm. 



The veins are not clearly seen, and there is only one indication 



1 Thomas (11) p. 86 & pi. vii, fig. 1. 



2 Stopes (10). 



3 Seward (11) p. 691 & pi. iv, figs. 67, 69 ; pi. vii. figs. 11, 12, 17; pi. viii, 

 fig. 32. 



