.  wenules form a right or nearly a right angle with the 
14 | ON GENERA AND SPECIES. 
fascicle terminate before reaching, or at the margin, their 
apices being free and unconnected ; and anastomosing when 
the apices of the branches of each proximate fascicle unite 
with one another, which they do in various ways, forming 
regular, square, rhomboid, hexagonal, or unequal sided 
meshes (areoles), When the primary veins are not evident, 
and all the anastomoses of about equal size, it is termed 
reticulate venation. 
Both free and anastomosing veins are spoken of as 
follows :—Simple, when each vein proceeds from the cost 3 
to the margin without branching. Forked, when they ` 
divide at an acute angle into two or more branches, after 
leaving the coste. Pinnately forked, when the primary S 
veins are scarcely defined, the venules dichotomously - 
branching. Pinnate, when the primary veins that run 
from the coste to the margin are distinctly defined, and — 
produce venules in regular order on both sides, forming a — 
more or less acute or oblique angle with their axis, 
The simplest form of anastomosing venation is when the — 
apices of simple or forked veins are combined or connected ; : 
by means of a vein close to and continuous with the mar- _ 
. gin, as in the genera Olfersia and Neottopteris, Pinnate and 
pinnately-forked veins anastomose by the uniting of the - 
apices of the venules of the proximate fascicles, which they 
do at various angles, from acute to nearly a right angle, or - 
even arcuate as in Menisciwm, or straight as in Blechnum. 
In most of these cases, the connected venules produce from 
_ the apex of their angular junction, or from their exterior 
sides, one or more outward directed veinlets (excurrent), 
which are either free or unite with the next exterior anas- 
tomose, thus forming in the latter case two or more rows 
of areoles between the primary veins. When anastomose 
