CLASSIFICATION. 25 
the form and nature of the mature sporangia for the fam- 
ilies, and of the sorus for the genera. It appears certain 
that the Hymenophyllacez contains the lowest forms most 
nearly allied to the Muscinee. The Hymenophyllacez 
probably forms the starting point for two or more series 
of families.” ) 
Sachs establishes seven families for all the known ferns, 
the Adder’s Tongue and Moonworts (Op/ioglossacee) being 
excluded from a place among the true ferns and assigned 
to a separate class. Prof. Daniel C. Eaton, of Yale, the best 
authority on ferns in this country, adopts a classification 
which is essentially the same as that of Sachs.* 
The following are the seven families of Sachs, with such 
representative ferns as are indigenous to this country: 
1. HYMENOPHYLLACE&, (TZ7richomanes radicans). 
2. GLEICHENIACE4, (vo American fern). 
3. SCHIZHACER, (Lygodium palmatum). 
4. OSMUNDACEX, (Osmunda regalis). 
5. MARATTIACEA, (vo American fern), 
6. CYATHEACEA, (No American fern). 
7. POLYPODIACE&, (Polypodium vulgare). 
If the OPHIOGLOssACE® is included, the Ophioglossum 
vulgatum will represent the family in America, leaving the 
second, fifth, and sixth without any representative in this 
country. 
The classification which I have adopted in this book is 
that of Prof. D. C. Eaton, as given in the last edition of 
Gray’s Manual, by whom the ferns of the United States are 
arranged in four sub-orders, as follows: 
I. POLYPODIACE, 3. OSMUNDACE&, 
2. SCHIZEACE, 4. OPHIOGLOSSACEA. 
* See article “Ferns” in Johnson’s Cyclopedia, vol. ii, p. 71. 
3 
