SCENT ORGANS IN TRICHOPTERA. A473 
in which event the long silky hairs, which are curved and so fit 
the normal amount of the convexity of the outer margin of the 
palpus, would slip out of their concavity over the “lip” of 
the outer convex edge and project as a “frill.” This action 
is often suggested while manceuvring the detached palpus in the 
dissecting dish. Again, if we suppose that the palpi by the aid of 
their muscular attachments to the stipes can be easily divaricated 
the one from the other and their inner surfaces exposed, it seems 
probable that the natural resilience of the hairs in the live 
animal would account for their erection, as they are inserted at 
right angles to the surface on which they stand, but in repose 
are flattened down upon it because the two palpi are then held 
closely apposed to each other. Perhaps also in the live animal 
the natural elasticity of the inner surface of the palpus may result, 
when exposed as a free surface, in its becoming swollen and convex, 
rather than as in spirit-specimens, concave. 
I do not think that the resemblance between the scent glands 
of Lepidoptera and those of Trichoptera can very profitably be 
carried into histological details. The papers on scent glands in 
Lepidoptera which I have consulted all show in one particular 
or another considerable differences from those of Sericostoma 
personatum, as, for example, in the presence of muscle-bands, in 
the arrangement of the trichogen cells, or the shape of the pore- 
canals and the position of the hair-tuft. 
I have to thank Mr, Martin E. Mosely for kindly giving me 
the material for this study, Prof. Maxwell Lefroy for allowing 
me to work in the Laboratory at the Imperial College of Science 
and Technology, and Mr. HE. Hargreaves for assistance 1n section 
cutting. 
v. LITERATURE. 
(1) Kirpy and Srence.—Introduction to Entomology. London, 
1826. 
(2) Picter, F. J.—Recherches pour servir a Histoire et 
VP Anatomie des Phryganides. Geneva, 1834. 
(3) SrepHens.—Ilustrations, of British Entomology, vol. vi. 
p. 148. London, 1836-1837. 
(4) Burmerster.—Handbuch der Entomologie, vol, ii. (2), p. 928. 
Berlin, 1839. 
(5) Rampur.—Histoire Naturelle des Insectes: Névropteres, 
p. 494. Paris, 1842. 
(6) Konenatr.—Genera et Species Trichopteroram, Pt.I. Act. 
Reg. Bohem. Soc. Se. Prague, vol. vi. 1851, p. 89. 
(7) McLacutan, R.—A Monographie Revision and Synopsis 
of the Trichoptera of the European Fauna. London, 
1874-80, pp. 223-224. 
(8) Umer, G.—Wytsman’s Genera Inseectorum: Trichoptera. 
Brussels, 1907. 
(9) Mutter, W.—Duftorgane bei Phryganiden, Archiv fur 
Naturgeschichte, 1887, p. 95. 
