397 
If, for instance, in a plant of any of the species of three genera 
comprising the Tribe Weissie, after fertilisation of the arche- 
gonium, the slightest deviation in the division of the cell by 
septa should take place, we should most probably have a 
variation of greater or less significance in the fructification :* 
it is, therefore, astonishing to note the almost complete immu- 
tability of the Natural Law which maintains, for trillions of 
generations, not only the generic but also the much more 
minute specific characters of so small a part as is the tooth of a 
deristome. And if such diverse forms have really been deve- 
loped from a unicellular organism how vast the intervening 
period must have been. 
Genus 5.—GYMNOSTOMUM. 
Beardless Moss. 
The Greek words of which the name of this genus is come 
posed are yuyvos (naked) and croua (mouth), referring to the 
naked orifice of the capsule. According to Bridel, this plant 
is frequently found intermixed with Phascum and Weissia, 
and has an erect simply-branched stem about half-an-inch 
high. The capsule is seated on a high and seldom arcuate 
fruit-stalk ; it is small, and loves to be near the habitations 
of mankind, growing in both barren and cultivated fields 
amongst grass. It is generally found in tufts, seldom growing 
solitary. In its fresh state it is a graceful little plant, but 
cannot be well observed without the aid of a lens. The 
essential generic characters are the naked mouth and the 
linear lancet-shaped leaves. 
Genus 6.—WEISSIA. 
This genus was instituted by Hedwigin memory of Weissius, 
Professor of Botany, Cidttingen. The plants are small, tender, 
and slightly branched ; the capsule bears a peristome of six- 
teen teeth. They must be looked for on moist banks or damp 
sandy places; they may frequently be found in crevices along 
with Fissedens, and sometimes on wall tops. The species of 
this genus present much variation in form, and will some- 
times be found very similar to Gymnostomums. The light 
green tufts have a beautiful cushion-like appearance, hence 
the English name for W. contraversa — green-cushioned 
Weissia. 
Genus 7.—SyYMBLEPHARIS. 
Wilson. 
This genus is so named by Mr. Wilson because the teeth 
of the peristome shut close in a cone when dry, the name 
literally meaning adhesion of the eyelids. Bridel names the 
only species of this genus collected in Tasmania Olomitrium 
* Hofmeister on the higher Cryptogamia. 
