238 PTILOZAMITES. 



Ptilozamites (Ctenozamites) Leckenbyi (Leckenby, 

 ex Bean MS.). 



[Quart. Journ. Geol. Soc. vol. xx. p. 78, pi. x. fig. 1, 1864.] 



1856. Odontopteris Leckenbyi, Zigno, Flor. foss. Oolit. vol. i. p. 111. 



1864. Ctenis Leckenbyi, Leckenby, Quart. Journ. Geol. Soc. vol. xx. p. 78, 



pi. x. fig. 1. 



1869. Cycadopteris Leckenbyi, Schimper, Trait, pal. veg. vol. i. p. 487. 



1875. Odontopteris Leckenbyi, Phillips, Geol. Yorks. p. 218, lign. 41. 



1880. Ptilozamites (Otenopteris) Leckenbyi, Nathorst, Beratt. p. 83. 



1892. Ptilozamites Leckenbyi, Fox-Strangways, Tab. Foss. p. 141. 



Type -specimen. "Wbodwardian Museum, Cambridge (Leckenby 

 Coll., No. 245). 



Frond bipinnate ; rachis stout, giving off pinna? at an acute 

 angle; the pinnae have slender axes bearing falcate segments 

 attached by the whole of the broad base, the apices are obtusely 

 pointed and directed upwards, in the distal portion the margin may 

 be finely denticulate ; several veins enter the base of each segment 

 and diverge slightly, and they branch dichotomously once or more 

 as they pass to the distal edge of the segment, which is formed of 

 the strongly bent posterior margin. 



This species does not appear to be represented by any specimens 

 in the British Museum Collection of Yorkshire plants ; the only 

 examples I have met with are those in the Leckenby Collection, 

 Cambridge, the best of which was figured in 1864 under Bean's 

 manuscript name, Ctenis Leckenbyi. 



I am indebted to Professor Nathorst for calling my attention to 

 a specimen in the Stockholm Museum in which the margin of the 

 segments is finely denticulate towards the apex. 



The species which present the closest agreement with Ptilozamites 

 {Ctenozamites) Leckenbyi are those described by Nathorst from 

 Scania, 1 and the still finer examples figured by Schenk 2 from 

 Persia. A specimen in the British Museum (No. 40,674) from 

 the Liassic beds of the south-west of England bears a strong 

 resemblance to Leckenby's Inferior Oolite species. 



Fontaine has described several examples of fronds not unlike 

 Ptilozamites Leckenbyi from the Potomac beds ; the species 



1 Nathorst (78 1 ), pis. vii., xi., and xii. ; (78 3 ), pL hi. 



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



