DISTRIBUTION OF THE MOEE PEOMINENT NATUEAL OEDEES. 281 



endemic in Trinidad; Dictyoxiphium is a monotype ranging from Panama to New 

 Granada and Venezuela ; and Dancea is a distinctly characterized genus of about a dozen 

 species, restricted to tropical America. 



Proceeding to the extra-American distribution of the genera, no fewer than forty-two 

 are widely diffused ; the curious and well-marked Anemia is represented in South Africa 

 by one species, Hemitelia in Australia by two or three species, and one of the South- 

 American species is also found in South Africa. 



Of the 545 species within our boundaries, 159 are endemic, and 293 others are 

 restricted to America ; in other words, nine elevenths of them do not extend beyond 

 America. Ninety-three species have a wider range — seventy-four being widely diffused, 

 ten African, one Asiatic, four Polynesian, three Galapagoan, and one has only been 

 found in Tristan da Cunha and America. 



A few more words respecting the distribution of ferns in Mexico and Central America. 

 A glance at the Table, p. 200, is sufficient to convince us that the fern flora of the 

 -southern countries is still very imperfectly known, especially that of Costa Rica ; though 

 since our Tables were drawn up the number of species has been increased to 134 (see 

 page 115 of this volume); and we may confidently assert that the better-explored Guate- 

 mala and South Mexico will yet yield a good many more novelties. The bulk of the 254 

 Guatemalan ferns in the Kew Herbarium were collected by Messrs. Godman and Salvin 

 in a comparatively restricted area. Fournier states * that the ferns of both slopes, 

 Atlantic and Pacific, of the Mexican Cordilleras are the same, with very few exceptions ; 

 indeed, he knew of only three from the Pacific side which were not found on the Atlantic ; 

 but then he had very few species from North Mexico, and not a single one from the 

 western State of Sonora. Eecent explorations have considerably augmented the number 

 of North-Mexican ferns. Our enumeration contains 100, and Pringle and Palmer's sub- 

 sequent collection would probably add four or five more. Considering the great falling 

 off, in fact almost total absence, of orchids and other epiphytal plants in North Mexico, 

 this number of ferns is at first a little surprising, because we are apt to associate them 

 with moisture and shade. On examining the composition of this fern-flora this surprise 

 will disappear, for it will be found that the genera Notholwna, Cheilanthes, and Pellcea, 

 genera specially characteristic of dry regions, largely predominate. The prevalence of 

 these genera in South Africa, Australia, &c, and their general distribution, is in similar 

 regions. After these genera hard-leaved species of Polypodium and Asplenium are the 

 most numerous ; the five genera named furnishing six tenths of the species. For 

 purposes of comparison, and to show that this peculiar flora extends northward into 

 Arizona and the adjoining territories, it may be added that, out of seventy-one ferns 

 enumerated by Engelmannf as inhabiting the United States territories west of 105° 



* Fournier, " Sur la distribution geographique des Fougeres du Mexique," Comptes Rendus, lxviii. 1869, 

 •pp. 1040-1042. 



f In Rothrock's ' Botany of Arizona &c.' 



