4.60 MR. B. F. CUMMINGS ON 
committed himself” to any direct statement as to the number of 
segments, though it seems more than likely, from an expression on 
p. 20 of his ‘ Recherches,’ that he regarded three as probable. 
Stephens (3), p. 148, assumes two to be the number. Burmeister 
(4) says that according to his experience the segments of the 
maxillary palpi are only two in number. Rambur(5) agrees with 
this, and makes the observation regarding the “ fluff ” on the inner 
surface of the two palpi that it is perhaps not produced until some 
time after the insect has emerged, as all specimens do not possess 
it. Kolenati (6) arrives at the astonishing conclusion that there 
are four segments, the second being galeate and the third and 
fourth more slender. McLachlan (7) is cautious, and says ‘“‘ they 
are probably 3-jointed, but the basal joint is scarcely separable 
from the sides of the face and the second joint... . is ill-defined 
and transverse.” A very brief and somewhat inaccurate descrip- 
tion of the palpi follows. MclLachlan’s account appears to have 
set the matter at rest in the minds of Trichopterists, for Ulmer 
(8) in 1907 echoes the former’s opinion that three segments are 
present, the first and second being ill-defined. 
It is necessary to point out at once that, as will be seen on 
examination of text-fig. 2, McLachlan mistook the cardo and 
stipes of the first maxilla for segments of the palpi. A paper by 
W. Miller (9) in 1887 appears to have been overlooked, for here 
not only is the maxillary palpus described correctly as one-jointed, 
but convincing evidence is brought forward showing that these 
palpi serve as scent organs. Miller observed the large tuft of 
elongate hairs (MclLachlan’s inelegant but expressive “ fluff”) 
on the inner surface of the palpi and compared them with similar 
hair-tufts in the males of some Lepidoptera. 
During copulation, one individual was seen ‘seine Palpen 
auseinander zi spreizen und die in denselben liegenden Haar- 
biischel zu entfalten,” so that they surrounded the head ‘ wie 
ein Heiligenschein.” A strong smell of vanilla was emitted. 
ll. SCENT ORGANS IN INSECTS. 
By “scent organ” the entomologist usually means those glands 
which, secreting an attractive odour and being confined to the 
male sex, are supposed at mating time to charm or stimulate the 
females. Such scent glands, well known in the Lepidoptera, aie 
situated at the bases of hairs arranged in tufts or at the bases of 
specially modified scales (called androconia) (10). Typical scent 
organs like these occur not only in the Lepidoptera (11) (12), but 
also in Coleoptera (Blaps mortisaga) (13), Blattide (15), and, as 
now appears, in Trichoptera (Sericostoma personatum). 
Another type of scent gland occurs in insects. This assumes 
the form of fairly long eversible tubular filaments, usually two 
in number, and is known in the males of some Lepidoptera, 
Spilosoma virginica, Arctia virgo, Haploé clymene (10), and in 
the males of the Cricket, Hadenwcus subterraneus (17). Similar 
