200 SECTIONAL ADDRESSES 
another attempt to determine the presence or absence of a velum with 
material which had been preserved in weak formalin, in which the delicate 
membranes of the velum are not at all well preserved, as I have noticed 
repeatedly in other species, but I have found sufficient indications of the 
velum in the form of very mucilaginous and swollen, as it were semi- 
hydrolysed, remains of the membranes. It is not clear whether the 
velum arises solely from the threshold or also from the glandular trichomes 
just beyond the front of the threshold, and until I obtain well-preserved 
material (in alcohol) the point cannot be settled. 
The threshold is approached, not from in front, but from the sides, as 
the projecting rostrum, the end of it resting on the enlarged stalk, obstructs 
direct approach. There is thus formed, as I have explained elsewhere, 
a sort of atrium, lined with great numbers of long, whip-like, glandular 
trichomes, the same sort occurring on the door itself, which forms the 
roof of the atrium. The capital cell of these trichomes is very long and 
slender, each secreting at its tip a droplet of mucilage. It may be that 
in the living condition these trichomes fill the atrium and act as a con- 
tributory velum. The actual entrance over the threshold is relatively very 
small and hedged about inside with up-jutting trichomes arising from the 
curved tissue shelf, in the front part of which is the pavement epithelium. 
This occupies a narrow strip on both sides of an angular ridge forming 
the front edge of the shelf. This ridge continues laterally to a point 
about half-way up the slope of the threshold, where the threshold pave- 
ment is very narrow. From this point it widens, fanwise, to the articula- 
tion of the door with the threshold, affording a wider out-sloping surface 
of application of the door thereto. The outer and inner zones are broader 
at the middle and narrower at the sides of the threshold. 
The door, as seen en face, differs a good deal from the previous species 
examined, in that it is nearly circular in shape, save for the segment cut 
off by the door edge, making it rather more than semicircular. The upper 
region is very thick, the inner course of cells being very deep and richly 
supplied with props, and capable of much compression. The middle 
piece gradually thins and is curved, and just above it is a weak, thinner 
region, marked by the presence of a number of small, sessile glands. 
This region lies between the upper region of the door, which is covered 
with a dense mass of the aforesaid whip-shaped, glandular trichomes, 
and a narrow strip above the door edge, which engages the threshold. 
The manner of this recalls the condition which is described above for the 
monanthos type—that is, the lower edge of the door is applied to a ridge 
in the threshold, over which it is bent; but the dimensions of the parts 
are different and the condition is not so striking. ‘The lateral reaches of 
the door are applied to the fan-shaped, outwardly sloping surfaces of the 
ends of the threshold. 
The actuation of this trap must be regarded (in the absence of actual 
observation) as being in the same manner as that of U. dichotoma, etc. 
The middle piece is held tightly against the ridge in the middle reach of 
the threshold by the thick lateral portions of the door, which exert 
a strong downward thrust. As a matter of observation, the lateral por- 
tions of the door are thick, in this being commensurate with its thick 
