48 DESCRIPTIVE CATALOGUE 



It shows, however, the characteristic lenticular furrows forming: 

 the corrugated surface of the pith-cast so commonly preserved 

 for plants of this affinity (cf. Cycadeomyelon, p. 54). 



The vascular cylinder appears to have been a monostele, in 

 the form of a single hollow cylinder, forming secondary wood. 

 There is no sign of a secondary cambium. 



The leaf-bases do not form a massive zone round the axis to 

 the extent common in the genus, and appear to account for no 

 more than about 3 cm. in the thickness of the stem. In tan- 

 gential view they are roughly rhomboidal, and measure about 

 1-5-2 cm. by about 1-1 '5 cm. vertically. They are mostly 

 weathered out, and b)' analogy one may judge that the ridges 

 betweeu thorn represent cork and a mass of ramenta 

 text-tig. 13). 



Text-fig. 13. -Rcunet/i/i'S Alli'hini. sp. noy. Drawing of a fmv leaf-V 



showing their shape, the ridges between them, and tlieir deeply 

 weutliereJ-out, centres. Nat. si/.e. 



Conts are buried among the leaf-bases in considerable numbers, 

 and will be easily recognised in PI. I. They are small, 

 measuring only about l'.">-2 cm. in diameter. Most of them 

 are much weathered out, and show no definite structures beyond 

 the central cone-receptacle. 



COMPARISON WITH. OTHER SPECIES. -The only other British 

 Lower Greensand Bennettites described in detail is B. (jibson- 

 ianits (see p. 28). 



The specimen differs notably from B. Gibsonianus in the si/.e of 



its leaf-bases, which are remarkably small, measuring only 1-5 



X 1 up to 2 x 1*5 cm., whereas in B. Gibsonianus they measure 



.'i x 2 up to 4 x 2*5 cm. ; and also in the smaller si/.e of the cones, 



