1'TILOZAMITES. 



23T 



characters of the frond of which it formed a part. The foruv 

 of the segment with the stout veins and lateral connections is 

 shown in Text-fig. 42. The epidermal papilla? (Text-fig. 43) have 

 already heen described in the remarks on the genus Ctenis. So 

 far as it is possible to base any comparison on the single specimen 

 of this type of Ctenis, which is not represented in the British 

 Museum, the frond probably agreed fairly closely with that of 

 Ctenis fallax, Nath., from the Rhsetic of Scania ; it differs from 

 Ctenis falcata in the greater breadth and coarser venation of the 

 pinna;. 



Genus PTILOZAMITES, Nathorst. 

 [Flor. Hoganits och Helsingborg, p. 21, 1878.] 



The genus Ptilozamites was instituted by Nathorst in 1878, 

 and defined as follows: "Folia petiolata lincaria, rcgulariter 

 pinnata, pinnis tota latitudine basis insertis, margine anteriore 

 recta vel paulum concava, posteriore rotundata, nervis dichotomis 

 radiantibus praesertini versus marginem posteriorcm. Differt 

 a Ptilophjllo margine anteriore pinnarum non subauriculata ab 

 Anomozamite a quo nonnullac species vix distinguenda) nervis 

 radiantibus non parallelis." ' 



At a later date this author proposed the generic name Ctenozamites 

 for fronds of the Ptilozamites type which are bipinnate and not 

 simply pinnate in their habit ; this genus has been employed by 

 Schenk in his description of a bipinnate frond Ctenozamites eycadea 

 from Persia. 2 



We may make use of the more recent designation as a subgenus 

 of Ptilozamites, and apply it to bipinnate fronds such as Ctenis 

 Leclcenbyi, Bean MS. The data we at present possess is insufficient 

 to enable us to decide with certainty the botanical affinity of 

 Ptilozamites, but the probability is that the fronds, having the 

 characters of Nathorst's genus, may be best compared with the 

 recent Cycad, Bowenia spectabilis, Hook. 



1 Nathorst (78 3 ), p. 21. 



2 Schenk (87), p. 5, pis. iii., iv., vi.-ix. 



