K.—BOTANY 20t 
dimensions, as seen in the sagittal section. The very great thickness of 
the hinge region of the door gives the impression of the need of an adequate 
and unusually large amount of available energy for actuation, and in this 
connection we recall that the trap is triangular in form (regarded trans- 
versely), and that the walls of four courses of cells are very thick. The 
roofing wall, as well as the lateral walls, were observed by Mrs. Johnson 
to be concave in the set condition of the trap. It may be argued that, 
roughly speaking, there is available rather more than 33 per cent. more 
energy than in a trap with only side walls. The trap is certainly a much 
more stalwart structure than usual, and can be compared in this only with 
the type of trap represented by U. globulariafolia. 
Tue Type U. GLOBULARIZFOLIA (Fig. 10). 
With this are several species having traps very much alike—namely, 
U. amethystina, U. tridentata, U. modesta, and U. Roraimense, and, 
according to Merl’s (1915) notes, U. bicolor, all New World, neotropical 
probably. 
The general form of this type of trap was described by Merl. It is 
a thick-walled and, in lateral view, well-rounded structure, with the stalk 
and entrance approximated. From the stalk leading up to the lower lip 
of the entrance there is a narrow but deep ramp, clothed along its ridge 
with long, backwardly curved, glandular trichomes in several rows. The 
overhang, which is massive, is forked, forming two strong antennz, also 
clothed with the same kind of trichomes in rows. All these rows of 
trichomes converge at the door, against which the innermost trichomes 
lie, forming a thick circle and, it would seem, an accessory velum at the 
door surface (somewhat as in U. monanthos), and a long, funnel-formed 
guide to lead prey to the middle region of the door, which is there clothed 
with sessile trichomes. 
The door is relatively small and nearly semicircular in outline, and is 
of nearly equal thickness from insertion to edge, though the inner course 
of cells is thicker toward the insertion. In some species, along the inner 
aspect of the free edge, runs a strip of beading in the form of three or four 
sharp ridges, which may serve to engage the edge of the door against the 
threshold. Its entire absence, however, in some species, throws doubt 
on such an interpretation. The angular divergence of the door and 
threshold is here much greater than in preceding forms, and the thrust of 
the former on the latter is very direct, the water pressure on the door 
having the effect of increasing the angular divergence and thus procuring 
a still more up-and-down thrust. 
The threshold is rather narrow and is supported on a deeply reaching 
shelf of peculiar and graceful form. The outer and middle zones are 
flat, the inner having a velum. The middle zone is very compact. The 
inner zone slopes away, facing inwardly. Its capital cells become more 
rounded and more loosely packed and always bear remains of enlarged 
cuticles, these cells having been subject to the general inflation of the 
cuticular investment giving rise to the velum. Whether the peculiar form 
of the tissue shelf which bears the threshold plays any part in the adjust- 
H2 
