1878. ] Aspidium spinulosum and its Varieties. 715 
The name itself has been used in part only, apparently to 
describe some form of A. spinulosum Sw. (spinulosum-americanum 
Fisch., MS., Index Fil. Moore, p. 104) but whether applied to 
the present form or to our American plants in general as the 
name implies, I have no means of knowing. Moore gives as a syn- 
onyme var. B. of Lastrea dilatata, a fern generally regarded as a 
distinct species by English authors. 
But whatever may have been its application in that form, in 
bringing it forward here under the present combination, it becomes 
an entirely new and as much an original name as if it had never 
been used at all. 
I have been led to restore A. Booftit to its specific value, and to 
retain Tuckerman’s name for it from the following consider- 
ations : 
The characters that seem to connect it with cristatum are, when 
more carefully examined, really no stronger than similar resem- 
blances between other and good species. 
For example, the sterile fronds of A. munitum of the Pacific 
States, and our northern A. acrostichoides are quite as much alike 
as the sterile fronds of Boottii and cristatum. Our common A. 
marginale and the Californian A. argutum sometimes so closely 
resemble each other as to suggest a closer relation than is 
accorded to them. These two species and A. filix-mas often appear 
to run together, having many similar resemblances, yet they are 
all three undoubtedly good species. Similar and equally strong 
resemblances may be found existing between many other species, 
and the puzzling forms of the small Botrychia are sufficient to 
show how little dependence can be placed, at times, on external 
appearances alone. 
It is sometimes difficult to distinguish small specimens of 
Cheilanthes lanuginosa from Notholena Parryi, and not an 
uncommon thing for fronds of Woodsia obtusa and Cystopteris 
Jragilis to become mixed through their close resemblance, and if 
this occurs among species belonging to entirely different genera, 
how much more likely is it to occur among closely related spe- 
cies. So that I cannot see why any argument drawn from such — 
resemblances should have more weight in any instance than in 
those mentioned. 
Few ferns are really more distinct than A. Boottit. Its indi- 
-= vidual character is even more pronounced than that of A. inter- _ 
