ON GENERA AND SPECIES. 45 



I have now to notice an important but yet incomplete 

 work, the " Index Filicum," a synopsis with characters of 

 the genera, and an enumeration of the species of Ferns 

 with synonyms, and references, &c., &c., by Mr. Thomas 

 Moore, Curator of the Garden of Apothecaries, Chelsea ; 

 the first part of this work appeared in 1857. The author 

 first gives a synopsis of the orders and tribes, followed by 

 a systematic arrangement and characters of the genera, 

 each genus illustrated by a woodcut showing the character 

 of the venation and position of the sori, also an analytical 

 table of the genera and their synonyms. 



With regard to the number of genera the author tells us 

 that he has endeavoured " to hold a middle course between 

 the excessive sub-division and the equally inconvenient 

 non-division of older genera," and that the classification 

 adopted is based on the plan on which the vascular struc- 

 ture is developed, in conjunction with the nature of the 

 fructification. He enumerates 186 genera*, which he 

 classifies under five orders, namely, Polypodiacece, Maratti- 

 acece, Ophioglossacece, Lycopodiacece, and Marsileacece. 



The following abstract will be sufficient to convey an 

 idea of Mr. Moore's method of classification. 



FILICALES, SPORE-CASES. 



ONE-CELLED. 



* Spore-cases furnished with a jointed ring, which is 

 usually nearly complete, sometimes rudimentary. 



ORDER I. POLYPODIACE^B. 

 || Ring vertical, nearly complete. 



Tribe I. POLYPODINE^E. 



1. Acrostichese (Ex. ElapJtoglossum, Schott. Acrostichum, 

 Linn.) 



* This includes ten genera of the orders Lycopodiaceae and Marsilia- 

 cese, which are not taken up in the present work. 



