240 HISTORY OP BRITISH PERNS. 



regards this one point. Their resemblance consists in both 

 growing up at the same time, and both putting out whorls 

 of deflexed branches, less numerous certainly on the fertile 

 stems ; but in other respects they differ, as, for instance, 

 in the growth of the apices of the fronds. The fertile ones, 

 terminating in a catkin which soon perishes, become blunt- 

 topped, while the barren ones continue to elongate at the 

 point and so become somewhat pyramidal. The barren 

 stems are also more slender than the fertile ones, and have 

 less inflated sheaths. It will thus appear, that this species, 

 in its habit of growth, holds a middle rank between that 

 group in which the fertile and barren stems are successive 

 and quite dissimilar, and that group in which they are 

 simultaneous and present no appreciable difference of struc- 

 ture. Something of the same kind occurs in E. umbrosum, 

 as will be found noticed under that species. 



The fertile stems, when they first shoot up, are almost quite 

 simple, and a few of them remain so, perfecting their cone- 

 like head, and then perishing. More usually, by the time 

 the catkin has become fully grown, the whorls of branches 

 from the upper joints will be seen protruded to the length of 

 from half an inch to an inch or rather more. Two, three, 

 or four, rarely more, whorls of branches are thus produced 



