CIEXIs. 231 



13,502. A specimen 13 cm. long and 4'5 cm. broad. The 

 numerous delicate veins are clearly shown, curving slightly 

 downwards towards the midrib ; the texture of the leaf appears 

 to be more delicate than in Tceniopteris. 



Gristhorpe Bay. Presented by Dr. Murray. 



Other specimens : V. 3674, ? 39,216. 



Genus CTENTS, Lindley & Hutton. 

 [Foss. Flor. vol. ii. pi. ciii. 1834.] 



1. Ctenis falcata, Lindley & Hutton. 



2. Ctenis, sp. 



In 1829 Phillips described a plant from the Oolitic rocks of 

 the Yorkshire coast under the name Cycaditex sulcicaulis, 1 and 

 in 1834 Lindley & Hutton 2 substituted the name Ctenis fatcata, 

 altering the generic designation on the ground that the venation 

 did not agree with that of Cycadites. The authors of the Fossil 

 Flora compared this plant with a species of Acrostichum and 

 with Palms, but considered that it should be included among 

 the Cycadaceffi. They proposed to apply the generic name Ctenis 

 to " all leaves having the general character of Cycadeoe, but with 

 the veins connected by forks or transverse bars." 



There has been considerable difference of opinion among 

 palseobotanical writers as to the position of Ctenis in the plant 

 kingdom ; some authors Sternberg, Brongniart, Schimper, and 

 others have regarded it as a Cycad, while by many others it 

 has been included among the Ferns. Without giving the history 

 of the views expressed as to the botanical position of Ctenis, we 

 may briefly consider the evidence on which the genus has been 

 referred to the Ferns rather than to the Cycads. 



In 1868 Schenk 3 discovered certain characters in a specimen of 

 Ettingshausen's species Tteniopteris asplenioides, which led him to 

 substitute the generic designation Ctenis. The veins of the broad 

 linear segments of the pinnate frond were found to agree in their 



1 Phillips (29), pi. vii. fig. 21. 



2 Lindley & Hutton (34), pi. ciii. 



3 Schenk (68), p. 220, pi. xxv. figs. 1 and la. 



