ACROGENS. 53 



Ferns themselves have in their foliage the peenliar veining of certain genera 

 belonging to the order of Yews inGyninogens ; they also approach Cycadaceous 

 Gymnogens in their simj^le cylindrical stems and gyrate foliage, which 

 bears the fructification on the margin. Nor are the Urn Mosses (Bryacese) 

 without their resemblance to the order of Yews when we compare some of the 

 larger species with the little Dacrydia of New Zealand, which are only a 

 few inches high. 



Alliances of Acrogens. 



MuscALES. — Cellular {or vascular). Spore-cases immersed or calyjArate 

 (i. e. either plunged m tie substance of the frond, or enclosed 

 within a hood having the same relation to the spores as an 

 involucre to a seed-vessel.) 



Lycopodales. — Vascular. Spore-cases axillarg or radical, one or many 

 celled. Spores of tic o sorts. 



FiLiCALES. — Vascidar. Spore-cases marginal or dorsal, one-celled, usualli/ 

 surrounded by an elastic ring. Spores of but one sort. 



