384 
Proceedings of the Royal Society 
of adult forms, and in this I have to acknowledge much valuable 
co-operation from my assistant, Dr J. M. Macfarlane. The result 
has almost surpassed my expectations. In all the species examined 
there is to be seen, immediately above the edge of the inflexed 
margin, a single line of small orifices alternating with the ridges of 
the corrugated annulus, and with their tooth-like prolongations when 
these are present. These orifices are the openings of canal-like 
fossse, from the bottom of each of wdiich a cellular nipple-like pro- 
cess or mammilla projects. These mammillae are the apices of what 
may be termed the Marginal Glands. The glands are of very 
large size ; the smallest I have seen — those of N. ampidlaria — 
being -Jy of an inch in length, while in some other forms — e.g., 
N. destillatoria, N. pliyllampliora, and an undetermined form 
(apparently allied to the hybrid N. Dominii), for which our Garden 
was indebted to the late Miss Hope of Wardie, they may reach the 
enormous length of yV of an inch. The nipple-like apex just men- 
tioned is never more than about 2^0 of an inch in length, and is 
the only portion of the gland which is free, all the rest being 
immersed in the parenchymatous substance of the annulus. The 
cells composing these glands are of somewhat small size, and are 
very numerous. Those in the immersed portion are, in a general 
way, disposed in lines which pass obliquely inwards and tow^ards the 
apex, the peripheral cells having a more or less transverse direction, 
wliile the central ones are longitudinally disposed. The superficial 
cells of the mammilla exhibit a beautiful columnar arrangement, 
being elongated at right angles to the surface. In some cases, 
especially in the larger forms, there seems to be a tendency to the 
formation of a central cavity from disruption from each other of 
the longitudinally disposed cells in the axis ; but I should not be 
inclined to attach any physiological significance to this circumstance. 
In shape the marginal glands vary somewhat. In N. awpidlarla 
the shape is ampullate, the nipple-like apex representing the neck, 
while the immersed portion, somewhat pointed at the base, and 
broadening upwards, represents the body of the ampulla. In the 
more elongated forms the shape is more or less cylindrical or 
sausage-like. 
The marginal glands, it will be seen, are remarkable not only for 
their large size, but still more for their immersed condition — the 
