Principles of Classification . 11 
ascertained, and therefore cannot be referred to any 
of the preceding classes. Ferns, mosses, and sea-weed 
are examples of this class. 
The Palm.ce, palm-trees, from their peculiarity of 
structure and appearance, were described by Linnaeus 
in an appendix to the twenty-four classes; but it ap- 
pears, from the researches and observations of succeed- 
ing botanists, that they may be arranged under the 
Hexandria, or 6th, class, or under Moncecia, or Dice- 
cia, the 21st or 2 2d class. 
Of the Orders . 
In the first thirteen classes of the Linnsean system, the 
orders are determined by the number of pistils, and the 
Greek words, Moncgynia, Digynia , Trigynia , denote 
one, two, or three pistils. The number of pistils is 
reckoned by the styles,or, when the style is wanting, by 
the number of stigmas, as in the gelder-rose ; and the 
number of pistils expressed by the Greek numerals, 
marks the order, as Monogynia, having one pistil, de- 
notes the first order, Digynia , Trigynia , Tetragynia „ 
Pentagynia , Hexagynia, Heptagynia , Decagynia , Z>o- 
decagynia , expressive of two, three, four, five, six, 
seven, ten, and twelve pistils, and Polygynia , signifying 
many pistils, all refer to corresponding orders of the 
class in which such plants are arranged, 
Didynamia , the 14th class, contains two orders; 1. 
Gym nospermia , so denominated from the seeds being 
naked, or uncovered, and they are almost always four 
in number, as in the dead-nettle ; 2. Angiospermia, ex- 
pressive of the seeds, which are numerous, being inclu- 
