LINDMAN, AMERICAN SPECIES OF TRICIIOMANES SM. 43 



Except the two last named, all these species are unfor- 

 tunately too imperfectly described, and without examinino- 

 the authentic specimens, nobody would understand them suffi- 

 ciently for the identification of a s])ecimen from another place. 

 An}' one who reads the descriptions of species just quoted 

 from the Gardener's Chronicle, will admit, that some of those 

 species may be identical with Tr. sphenoides, but unluckely 

 the}' can also be different from this. They were evidently 

 not examined by the author in a sufficient degree of enlarge- 

 ment. Even the three species, which I intend describing as 

 new in the following pages, I do not therefore venture to 

 unite with any of Jenman's, although it is possible, that uiy 

 Trich. fontanum {ng. 26) is either setiferum Jenm. or pinna- 

 tinerva Jenm.. and my Tr. myrioneiiron (fig. 28, 29) identical 

 with fruticulosum Jenm. 



The numerous forms of the sphenoid c s-gro\x\) — interme- 

 diate forms uf which will perhaps be discovered in the future 

 — ])robabl3' owe their origin to their ])eculiar habitats. These 

 small and primitive plants grow in old forests, which are 

 often of small extent, but surrounded by extensive and dry 

 districts (>.campos ), where the Hymenophvllaceae cannot live; 

 nor is it likely they can be carried away by any means from 

 their closed and sheltered domicile, in the moist and shady 

 localities in the depth of primeval forests. Some smaller 

 species are often hidden on the ground and sprinkled amongst 

 the tufts of moss on wet stones, round a spring or a little 

 brook. We must admit, that they are, in their natural state, 

 vigorous and in man}- cases widely-distributed dwellers of 

 the forest, but on the other hand they are now limited to 

 comparatively small s])ots, isolated from each ofher for thou- 

 sands of years, and separated by wide spaces, which these 

 small and peculiar ferns are prohibited from crossing. On 

 account of these circumstances, we cannot wonder, that a 

 oertain type of Trichomanes has produced various but closely 

 allied species (or varieties, or races) in the far distant and 

 solitary localities of its geographical area. The more primi- 

 tive and minute a fern is, the easier a little variation can 

 cause a (really or seemingly) different type (for instance the 

 elongation of the stipes, the increase of spurious venules, the 

 enlarged involucre, the reduction of lobes). I think it is bet- 

 ter in this case, that we try to fully account for all the 



