PTILOZAMITES. 23T 



characters of the frond, of which it formed, a part. The fornii 

 of the segment with the stout veins and lateral connections is 

 shown in Text-flg. 42. The epidermal papilte (Text-fig. 43) have 

 already been 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., fi-om the Ehsetic of Scania; it differs from 

 Ctenis falcata in the greater breadth and coarser venation of the 

 pinnae. 



Genus PTILOZAMITES, Nathorst. 

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



The genus Ptilotamites was instituted by N"athorst in 1878,. 

 and defined as follows: — "FoUa petiolata linearia, regularitcr 

 pinnata, pinnis tota latitudino basis insertis, margine anteriore 

 recta vel paulum concava, posteriore rotundata, nervis diohotomis 

 radiantibns prsesertim versus marginem posteriorcm. Differt 

 a Ptilophyllo margine anteriore pinnarum non subauriculata ab 

 Anomozmnite a quo nonnuUae species vis distinguenda; nervis 

 radiantibns non parallelis." ' 



At a later date this author proposed the generic name Ctenozamites 

 for fronds of the Ptihzamites type which are bipLanate and not 

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

 Schenk in his description of a bipinnate frond — Ctenozamites cycadea 

 — from Persia.^ 



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

 of Ptilo%amites, and apply it to bipinnate fronds such as Ctenis 

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

 to enable us to decide with certainty the botanical affinity of 

 Ptilo%amites, 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 (TS^), p. 21. 



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



