OTOZAM1TES. 



71 



Type. Specimen of frond. Berlin Museum. 



Bunker thus denned the species in 1846: " Pterophyllum 

 fronde impari-pinnata, pinnis oppositis subrectis elongatis lineari- 

 bus acuminatis subremotis, aeque distantibus angulo acuto adnatis, 

 nervis obsoletis quinis vel senis, rhachi crassa subtereti laevi." 



He speaks of each pinna having five or six equal and thin 



veins, and shows this venation in the slightly magnified portion 



represented in fig. 5a, pi. ii. Bunker's figures certainly appear 



to justify his choice of the genus Pterophyllum as regards the 



manner of attachment and distal terminations of the segments. 



^Reference has already been made, in speaking of the various 



sources of error connected with fossil cycads, to the very different 



appearance presented by a frond when viewed from the upper 



and lower surface. In the present instance it is quite possible, 



and, indeed, considering all the facts before us, I believe very 



probable, that we have in Bunker's fig. 5 a view of the under 



surface of the frond. The rachis is seen to project considerably 



above the level of the pinnae, and the latter are either attached 



by broad bases to its margin, or pass underneath and are united 



to the face of the rachis which is pressed against the rock 



surface. The venation, as Dunker describes and figures it, does 



not accurately correspond with that of the English specimens 



which I have ventured to refer to this species. If, however, 



Bunker's drawing represents an imperfect fragment seen from 



below, it is very likely that we should find a somewhat different 



appearance presented by the veins to that which is seen in the 



more perfect pinnae of the English fronds. If specimen V. 2360 



(PL I. Fig. 2) be compared with Bunker's pi. ii. fig. 5, the 



striking resemblance between them in the form and arrangement 



of the pinnae cannot fail to be noticed. The English specimen 



seen from the under side would present an appearance very similar 



to that of Bunker's frond. Turning to Schenk's account of the 



same species, we find he follows Miquel in adopting the generic 



name Dioonites in preference to Pterophyllum. Schenk includes 



in this species the specimen figured by Bunker as Pecopteris 



linearis, which the former regards as a badly preserved fragment 



of Dioonites Goppertianus ; this does not seem probable, so far as 



the figures enable us to form an opinion. This author extends 



the original diagnosis of the species, and points out that the pinnae 



are attached to the upper surface of the frond axis ; his figure 



