CYCADITES. 27 



determinations which do not rest on other characters than those 

 of external form. Another species from the same beds, C. ? 

 planicosta, Heer, 1 is founded on imperfect pinnae, but in this 

 case Heer definitely admits the doubtful value of the name. 

 The specimen described by the same authority from the Tertiary 

 beds of Schaffhausen as Cycadites Escheri- is very likely a 

 cycadean stem, but the genus Cycadites has been restricted to 

 fossil fronds, and Heer's stem fragment should be referred to 

 some other genus, in order to avoid the confusion likely to arise 

 from using the name in a more comprehensive sense. Dawson 

 has described some fronds from the Middle Cretaceous of the 

 Kocky Mountains, which he names Cycadites Unjuga* and 

 compares with Heer's Cycadites Dicksoni. The two figures of 

 the Canadian specimens do not appear to agree as regards the 

 Cycadites form of pinna : in Fig. 2 each pinna appears to have 

 several parallel veins, and the general habit seems different 

 from that in Fig. 2b ; if Fig. 2 be an accurate representation 

 of the specimen, and the vein-like lines are not the draughts- 

 man's shading, it could hardly be accepted as a true Cycadites. 

 Feistmantel figures a fragment under the name of Cycadites 

 constrictus, Feist., 4 and speaks of a midrib in the basally con- 

 stricted pinna3 ; the figure does not show any distinct midrib, 

 and leaves one in doubt as to the wisdom of choosing the genus 

 Cycadites. 



1. Cycadites Romeri, Schenk. 



[Fig- 1-] 



1871. Cycadites Romeri, Schenk, Palseontographica, vol. xix. p. 229, pi. xxxii. 



figs. 1, la. 

 1874. Cycadites Romeri, Schimper, Trait, pal. veg. vol. iii. p. 552. 



Type. Portion of a frond. Berlin Museum. 



The following definition is given by Schenk for this species : 5 



1 Heer, Fl. foss. Arct. vol. iv. pt. ii. pi. iv. fig. 16. 



2 Heer (A. 1), FL Tert. Helvet. p. 46, pi. xv. 



3 Dawson (1), p. 20, pi. i. fig. 2. 



4 Feistmantel, Gond. Flor. vol. i. pt. iv. p. 25, pi. vii. fig. 10. 



5 Schenk (A. 2), Paloeontographica, vol. xix. p. 229. 



