462 MR. B. F. CUMMINGS ON 
maxillary palpi, a position in which, I believe, they are unrecorded 
in the Lepidoptera. 
Although Kellogg (18) bas described and figured special 
plumules and scale-lke hairs on the wings of 'Trichoptera, 
é.g., Mystacides punctata, which function probably as andro- 
conia, scent organs have not, I think, been hitherto examined 
anatomically in this Order, for even in the paper in which 
Miller gives us an account of his discovery of the true function 
of the extraordinary palpi of Sericostoma, no account is included 
of the structure either of the palpi or of the glands. 
In Sericostoma they differ in position from the scent glands of 
other insects. Scent glands are found on the abdomen or on 
the thoracic appendages. According to Berlese [(12) p. 525] 
odoriferous scales have been found on the palpi of some Satur- 
nine butterflies, but he does not say whether they are the labial 
palpi or the maxillary palpi. Probably they are the former. 
Well-developed and characteristic scent organs occur in the 
labial palpi of an Indian butterfly, Bertula chalybialis; this, 
and the case of Sericostoma personatum, form the only well 
authenticated instances known to me of scent organs in the 
head, in the one case on the labial palpi and in the other on 
the maxillary ‘palpi. 
When not in use, the hair-tufts on the legs of the Lepidoptera 
with scent organs are often concealed in cavities, just as the hair- 
tuft of Sericostoma is concealed within the cavity of the imner 
surface of the maxillary palpi. 
I anticipate that among the many strange modifications of 
the maxillary palpi of the males of many genera in the Family 
Sericostomatide, sometimes densely clothed with large black 
striated scales (Gara and Lepidostoma), scent organs will be 
commonly found and their occurrence in the Trichoptera be 
very generally recognised. 
It is evident that scent glands in insects are of fairly common 
occurrence and have been independently acquired over and over 
again. According to Berlese, hairs like androconia have been 
described from the wings of Diptera. 
i. Tar MAxituAry Paupt or SERICOSTOMA PERSONATUM. 
Each palpus in outline is something like a half-moon. The 
outer surface is convex and strongly chitinous, dark brown in 
colour, with scattered short black hairs. The inner surfaces of 
the two palpi, which are carried closely apposed to each other, 
are concave, but their concavities are filled up to a level surface 
with an extremely thick felting of very long golden-yellow silky 
hairs. Until the palpi are separated with a needle the one from 
the other, the yellow felting lining the inner sides cannot be 
seen, or seen only with difficulty by looking at them edgeways 
from in front. 
Both the palpi are held vertically with their broad surfaces facing 
