XVlil 
ihe great division of ferns having a ringed capsule, and 
sometimes now called true ferns, which are ranged in 
two — indusiate and nonindusiate — series, and of a few ad- 
ditional genera grouped in four additional sub-orders of 
genera without this encircling ring, the capsules being sunk 
in a fleshy or corky receptacle. These additional sub-orders 
are Osmundacese, Schizacese, Marattiacese, and Ophio- 
glossacese ; the genera are few, and they are not arranged 
in Tribes. The true ferns have a well marked similarity 
between the two series, which as it were represent one 
another, the indusium only presenting a difference ; Cya- 
thea and Alsophila, for instance, Asplenium and Gynmo- 
gramme, Cheilanthes and N othoclilaena, &c. 
25. Species appear to ally one genera in same series 
to another, (Meniscium cuspedatum and P. urophyllum) ; 
D. (odont) repens is a doubtful Lindsaya. These are 
Indian plants, and offer a good field for further observation. 
Light may be thrown on the true relationship of genera, 
by a careful study of variable ferns, whose range of vari- 
ation and number are greater than was supposed, to the 
obliteration of several named species. A wide field is 
still therefore left for future observation and research in 
scientific pteridology. 
2G. Ferns are commonly spoken of by their subge- 
neric name, which in many cases was that of former clas- 
sifications ; but in writing out lists for guidance, it is better 
to add this last in brackets, Thus: Nephrodium canum 
a lastrsea, should be Nephr. (lastr.) canum ; Diplaziun\ 
