ZAMITES. 75 



V. 2123. PI. I. Fig. 1. Rachis 10cm. long; the pinnae more 

 closely arranged, and resemble on a rather larger scale Schenk's 

 figures of this species. The auriculate character of the bases of 

 the segments distinctly indicated, also the median groove in the 

 axis of the frond. Numerous fiue veins distinct. Cf. the upper 

 unfigured portion of V. 2360. 



There is an imperfect specimen of this species in the Museum 

 of Practical Geology, Jermyn Street, in which the auriculate 

 base and venation characters are fairly well shown. 



Genus ZAMITES, Brongniart. 

 [Prodrome, 1828, p. 94.] 



In describing some Japanese examples of the Wealden cyca- 

 dean frond named by Ettingshausen l Pterophyllum Buchianum, 

 Nathorst 2 draws attention to certain characters in the pinnae 

 which, he considers, exclude the species from Pterophyllum or 

 Diuonites, in which it has generally been placed by other writers. 

 He finds that the segments are somewhat narrower towards the 

 point of insertion, and apparently laterally attached to the frond 

 axis, thus differing in essential features from the above-named 

 genera. The splendid series of specimens in the Rufford Collection 

 confirms Nathorst's remarks with regard to the narrowing of the 

 pinnae towards the point of attachment to the rachis, but on the 

 other hand, the English examples show a manner of attachment 

 of the pinnae more in accordance with the genus Zamites^ the 

 pinnae being inserted on the upper surface of the rachis, and 

 apparently along two more or less distinct lines. The new genus 

 Zamiophyllum, proposed by Nathorst for this species as a substitute 

 for Pterophyllum or Dioonites, on the ground that the characters 

 do not conform in all essential respects with any existing genera, 

 cannot well be retained in the light of the more recent facts 

 afforded by the large series of English specimens. The genera 

 Dioonites and Pterophyllum are quite unsuitable for this species, 



1 (A. 4), Abh. k.-k. geol. Eeichs. vol. i. 1852, p. 21, pi. i. fig. 1. 



2 (A. 3), Denkschr. k. Ak. Wiss. vol. Ivii. p. 46. 



