148 DR. J. BRAXTON HICKS ON UNDESCRIBED SENSORY ORGANS IN INSECTS. 
hairs of the general integument is a matter of much difficulty, compared with that of the 
members where the nerve can be easily traced throughout its course. 
I now wish to call attention to the anatomy of the " barrel-shaped" organs (as they 
ailed) on the proboscis of the Lepidoptera. They are found in almost aU 
X 
the interior of the 
of English Butterflies and Moths. The genera Pontia, Pieris, Gonopteryx, and the 
Sphingidce, are free from them, as is also the rudimentary proboscis in the Bombycida and 
Tiger Moths. Perhaps they are shown best in Argynnis Paphia and Vanessa Atalanta 
among the Diurna, whilst among the JSToctua Mormo and Tryphcena possess them exceed- 
ingly well marked. In those species where they are not present, dwarfed hairs are found, 
m rows on the proboscis ; but whether they are in the same position as the barrel organs 
would have been in, I cannot decide. 
The form of the barrel organs is very variable ; but they may be divided, so far as I 
have had the opportunity of examining hi British Lepidoptera, into two divisions— the 
simple and the winged ; the latter I have found only in the Moths, whilst the simple are 
confined to the Diurna. The simple form is shown at PL XIX. fig. V, 1, which represents 
that of the Argynnis Paphia. They are flattened in one direction. The winged are 
shown at PI. XIX. fig. V, 5, being those of Mormo Maura (Moth). The section at 6 
indicates the position of the wings on the body of the organ. 
The essential part of the barrel organs is a tube more or less dilated towards the 
middle, contracting again towards the apex, and terminating in a nipple-like point,-the 
membrane of this papilla and for some distance around its base being very thin and deli- 
cate ; and, at the point where this thinning commences, a very delicate tissue stretches 
or S an - A nerve can be traced up to this membrane for that 
certainty, as is shown at figs. V, 1 & 4, in Argynnis Paphia. I am tolerably certain that 
a delicate filament passes to the apex of the papilla (fig. V, 2) ; or if that is not the true 
interpretation of the appearance, then I think it must be produced by a very delicate 
tube passing from the apex of the papilla into the interior of the barrel organ. This point 
is difficult to settle on account of the delicacy of the parts to be investigated. In the 
Vanessce and many other Diurna, there is a ring of eight spines around the papilla, which 
spring from the part where the thinning commences ; and in the Moths there are seven or 
ht rings springing from the whole length of the barrel organs, ending at the point just 
mentioned. The upper points of the rings and of the spines, as in Vanessa, do not, I 
believe, ever extend to the length of the papilla. That these organs, where they exist, are 
used for some refined sense, one can hardly doubt, but of what nature it is very difficult 
to decide. Whether it is to the sense of touch that they confine that highly-developed 
variety of it which we call taste, we are not at present competent to judge. «. 
mical resemblance of these organs to that on the palpus of Forficula will be apparent 
tO 8.11. 
In considering what functions we are to assign to the various structures I have just 
il i * WG ^^ t0 bear in mind that a t0 ° stron " de Pendence on analogy of position 
ot the diflerent parts of Insects, and of the Invertebrata in general, to those of the higher 
animals will tend to mislead us ; for as the ganglionic nervous system is itself diffused far 
beyond the state it is m the Vertebrata, so we may possibly find that the special sensations 
eig 
The 
