Explanatory. 
the first of the two sub-classes into which Acrogens are divided. 
The number of known living species of ferns has been estimated at 
2,000, and of fossil ferns there are some hundreds already known 
of species entirely distinct from those now existing. Of these 
it may be added for the information of any one who may be 
travelling in that direction that Dr. Hochstetter mentions “a locality 
on the West Coast, about 7 miles south of Waikato Heads, where 
beautiful fossil ferns are imbedded in grey argillaceous strata alter- 
nating with sandstone layers and small coal-seams. 
The distribution of species is remarkably wide, and this, as 
well as another fact, to be hereafter mentioned has led to great 
confusion of nomenclature. Thus, a local botanist, finding a fern 
new to him, bestows upon it a name and when it has gained some* 
currency, it perhaps falls into the hands of one better informed on 
the subject, who forthwith shows the plant to be one which has^ 
already received two or three names from presumed discovered 
in various parts of the world. In this manner,"' one of the NeW' 
Zealand ferns has received no less than eight different names! 
Dr. Hooker comprises 117 species in his Flora Novae Zealandiae. 
of which he says, 30 are of such wide distribution that they may 
be termed cosmopolitan or mundane ; 30 inhabit South America 
61 Australia and Tasmania ; 10 are European ; several which are 
not known to be natives of Australia or America, have been founc 
in the lofty mountains of Java; and others in South America' 
Still he gives 42 as peculiar to New Zealand, although it is noi 
unlikely that they may yet be found common to other parts o 
the world. Since the publication of his work several other specie; 
have been discovered in these islands. 
Before proceeding further, it will be necessary to beconn 
acquainted with the names of the various parts of ferns ; and alsc 
with a few botanical terms, the use of which we have been unabl 
altogether to avoid. The rhizome is the underground rootin/ 
stem ; the stipes is the stalk from the ground up to the commence 
ment of the leafy part ; the continuation of this stalk is callei 
the rachis ; the principal veins branching from the rachis ar i 
costae and those branching again from the latter are termed costulei 
veins , or veinlets ; rhizome, stipes, rachis, costae and costule 
forming as it were the skeleton of the fern. When the veins d 
not branch they are simple ; when they branch and the branche 
do not meet or run into one another they are forked and free 
when they branch and unite again so as to form a network the 
are anastomosing ; in such case the spaces between the vein; 
within their meshes, if we may so speak, are termed areoles. Th 
whole leaf is called a frond , its primary divisions are pinnce ; an*. 
* Pteris incisa, Dr. Hooker describes it as P. Vespertilioni 
but we have given the former name in accordance with a work moi 
recently published by Sir William J. Hooker, who decides that it 
the oldest name of the eight. 
4 
