. ON GENERA AND SPECIES. 15 
primary veins, they thus become parallel with the cost», 
and are then called transverse. In many cases the venules 
produce veinlets in an irregular manner, which either anas- 
tomose, or terminate within the areoles. When directed 
outwards they are termed ewcwrrent, and recurrent when 
directed inwards; this is termed compound anastomose 
venation, In many cases, both in free and anastomose 
venation, the apices of the venules and veinlets is thickened 
_ (clavate) in the form of a gland, 
RECEPTACLES. 
The receptacles are the sites upon which the sporangia 
are seated, and are generally thickened points, or length- 
ened portion of some part of the venation. In position 
they are called terminal when on the apex of the veins or 
their branches ; lateral when on the sides of the veins; | 
axillary when on the forking ; compita] when on the 
angular crossing or points of confluence of two or more 
-venules or veinlets. They are superficial or immersed in 
_ the substance of the frond, or elevated above its surface, and 
then columnar or globose, When in the form of a point 
or dot they are termed punetiform, and, when lengthened, ` 
elongated or linear; and amorphous when of no defined ` 
form (as in Acrostichum). E 
SPORANGIA. 
_ The spore cases or sporangia are the organs which con- ` 
: the receptacles. "They are thin and transparent, or horny, 
tain the reproductive spores, and are borne in masses upon 
