C/^,(A^ f :^i<^J^ 



xxvrn] 



FRONDS 



13 



Cycas. The presence of a strong midrib and the absence of lateral veins 

 are distinguishing features: the lower margin of the lamina is frequently 

 deourrent (fig. 387, A). In O. circinalis the pinnae may reach 40 cm. in length 

 with a fairly uniform breadth of 2 cm. A frond of this species in the British 

 Museum, not quite complete, has a length of 112 cm.: on the lower part of 

 the raohis strong spines replace the leaflets and near the apex of the leaf 

 concrescent pinnae form a continuous lamina traversed by seven ribs and 

 dissected at the margin into acuminate teeth (fig. 384) : some of the pinnae 



Fig. 384. Cycas circinalis, abnormal frond. (From a specimen in the British Museum. ) 



are forked as in Cycas Micholitzii'^ (fig. 385). Several years ago I noticed a 

 similar instance of concrescence in a small plant of C. circinalis in the Royal 

 Gardens, Kew (fig. 387, 1). In Cycas Micholitzii the pinnae, reaching a length 

 of 20 cm., are repeatedly and deeply forked (fig. 385, A, B; fig. 400): the 

 pinnae of C. Rumphii var. bifida^ are also deeply dissected. Cycas Beddomei 

 has very narrow pinnae (15 cm. x 2 mm.) similar to those of the Wealden 



1 Thiselton-Dyer (65) B.; Bot. 



2 Thiaeltou-Dyer (02) p. 560. 



'. 1909, Tab. 9242. 



