Index filicum: a synopsis, with characters, of the genera, and an enumeration of the species of ferns, with synonymes, references, - 1857. - ADVERTISEMENT. THE attempt now made to produce a Catdope of Ferns arranged on some uniform plan, of convenient bulk and moderate price-as complete withal as a diligent research in the publications accessible to him has enabled the author to make it, has sprung from the acknowledged want of some recent enumeration of the species of Ferns, embodying the modern principles of classification. Such an enumeration, required, in order to render it fully intelligible, that a synopsis of the Genera of Fcrns should be prehed. I t seemed o necessary to its utility, that the Catalogue itself should indicate under the adopted species, the following particulars, namely - l references to the most useful general publications, as well as to those detached memoirs, in which they may be classified or described 2 an enumeration of their sponymes 3 references to figures and 4 a summary of their known habitats sacient to illwitrate their geographical range. It will be obvious, that in order to render this infonnation accessible as speedily as practicable, a thorough criticism of the synonymy could not be attempted, for this would have involved the actual labour of a complete Species Blicum, and conld not indeed have been accomplished, without long delaying the publication of the list. Free use has consequently been made of the statements, critical or otherwise, of those botanists who have devoted attention to the subject, the whole being blended with such personal information as the author has been able to bring to bear on the subject. The work is consequently to be regarded as, mainly, a compilation. It has however been the endeavour both of the author and the publisher, to render it, as such, not only useful and readily available, but a. 9 free from error as possible. To this end, the greater number of the references gives, have been actually examined - a few only of those made to less accessible works, having been taken on trust. In the prefixed Synopsis of the Genera, the author has aketched out what appears to him the most intelligible arrangement, as well as endeavoured to simplify the definitions of the generic groups. As regards the genera themselves, it has been an endeavour to hold a middle conrse, between the excessive sub-division and the equally inconvenient nondivision of the older genera. The system of classification adopted, is that based upon the joint recognition of 1 the plan on which the vascular structure is developed, and 2 the nature of the fructification. This is the best plan yet devised, and if carried out with moderation, not to excess, and with a well-defined appreciation of what constitutes an important distinction, it is open to fewer objections and presents fewer difficulties than my other plan which has been suggested. It has nevertheless appeared, that in the application of this system, the number of genera has been hitherto too much extended consequently those which are regarded as less necessary or most trivially characterized, dependant on the slighter venal and other differences, have not been adopted while those based on the broader differences of venation, snch for instance as are presented by free-veined and net-veined species, and again among the latter snch as occur in a uniform or a pinnate plan of reticailation, or in the presence or absence of free included veinlets, have been unreservedly admitted... --This text refers to the Paperback edition.