NOTICES OF BOOKS. 93. 



appendages." We only trust that Mr. Lawrence will persevere in this 

 line of his art, and we should have uo fear of his rapid improvement, 

 if he do but meet with the encouragement he deserves. 



The arrangement here adopted, and the greater number of the divi- 

 sions and genera, are acknowledged to be in accordance with Mr. J. 

 Smith's views, though the author does not agree with Mr. Smith in 

 the position he has assigned to several genera and species in his sys- 

 tem ; but he pays a just compliment both to him and Dr. Presl for the 

 light which their investigations have thrown upon a family of plants, 

 " the genera of which had been cumbrous and unmanageable, by the 

 accumulation of heterogeneous masses of species." We find 702 spe- 

 cies here enumerated (of which no less than 146 are described as new), 

 included in 107 genera. Mr. Brackenridge had foreseen where his 

 greatest difficulty lay, viz. in a just limitation of species, an error into 

 which those, who have had greater advantages than himself, have too 

 frequently fallen. To avoid this error it is not only necessary to con- 

 sult a great number of works, which the libraries of Washington do not 

 possess, but to have extensive suites of specimens from various coun- 

 tries, and compare one with another, with an unprejudiced mind, un- 

 shackled by the views of others, and see how the varieties pass into 

 supposed species. "Of those which are here characterized as new, 

 some probably have already been published, either as species which I 

 have failed to identify, or in receut works" (and there are many such,) 

 " which were not accessible to me. I can only say that I have endea- 

 voured to prevent, as for as possible, such an occurrence, by diligently 

 consulting all the authorities I could command. And in the large col- 

 lection of Ferns made by the Expedition, most of them on islands in 

 the Pacific Ocean, which have not heretofore been much visited by 

 botanical collectors, and where humidity, heat, and shade, elements 

 conducive to the production of Ferns, are-combined in a high degree, 

 surely as large a number of new species as are here proposed was natu- 

 rally to be expected." Our own investigation of Ferns from the Pacific 

 Ocean lead to rather diflFerent conclusions, and are more in harmony 

 with the observation towards the close of the Preface, to the eflect that 



I 



one and "the same Fern has frequently been met with in two or more 

 remote parts of the globe, clearly showing that species of this Family 

 have a more extensive geographical range than has been generally sup- 

 posed.'' 



