INTRODUCTION TO CRYPTOOAMIC BOTANY. 507 



of mosses, it seems impossible to make any arrangement which 

 shall be quite satisfactory. That which I have adopted is 

 certainly open to many objections, and the same may be said 

 of every existing classification. 



ALLIANCE V. 



FiLicALES, BerL 

 FiLicALES and Ltcopodales, Lindl. 



Spores producing a prothallus by germination or by cell- 

 division homologous with germination. Archegonia formed 

 in the prothallus, producing, after impregnation, a distinct 

 sporiferous plant. 



569. The two groups of Cryptogams associated by Dr. 

 Lindley, under the names Filicales and Lycajpodales, are so 

 closely united by means of Ophioglossoxew, that I have no 

 hesitation in comprising all under one head, characterised by 

 the formation of a distinct prothallus. Even if the general 

 denomination of Filicales should not be approved, as applied . 

 to all the natural orders included under it, their intimate rela- 

 tion is not invalidated by the adoption of a name which might 

 seem to indicate a closer resemblance between the tribes asso- 

 ciated under the Lycopodal group, and that of Ferns, than 

 actually exists. Ophioglossacecti, however, scarcely bear a 

 closer resemblance to Ferns than Salvinia; and while their 

 aestivation is straight, certain Lycopodales, as Pilularia, pos- 

 sess a circinate aestivation. 



I. FiLICES, JUSS. 



Fronds circinate when young, simple or variously divided, 

 the fertile often of a different form from the sterile, bearinsT 

 on their under side little heaps (sori) of subglobose sporangia, 

 mostly furnished with a distinct and often elastic ring, naked 



