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WEST 
surface are the organs which have been so frequently mentioned as "hairs," "hair-like 
appendages," "trumpet-shaped hairs," &c. That these are the immediate agents in 
holding is now admitted by almost all; it will be convenient to term them '"tenent" 
hairs,' in allusion to their office. The delicacy of their structure in the fly ; the bend 
near their extremity, after which on each supervenes an elastic membranous expansion, 
capable of close contact with a highly polished surface, from which a very minute quantity 
of a clear, transparent fluid is emitted when the fly is actively moving ; all this is now 
admitted by the best observers. It simply remains to add that the tubular nature of 
the shaft of the tenent hairs on the foot of this insect has been surmised, although its 
minute size and homogeneity hardly permits of the surmise being actually confirmed by 
visual inspection. At the root of the pulvillus, on its under- surface, is a process, which 
in some instances is short and stotit, in others long, greatly curved, and tapering to its 
extremity {Scatophaga), setose (Empis), plumose {Hiptpobosciclce) , or, in one remarkable 
example (Ephydra) , so closely resembling in its appearance the very rudimentary pulvillus 
with which it is associated, that I was for some time unable to decide whether it was a 
third lobe of this organ, or, with the other examples named and to be more fully 
described hereafter, a peculiar tactile hair, which is present, in some modification or 
other, in all insects, so far as my present experience goes. This tactile hair has been 
considered by two excellent observers* to be a spring, by the help of which the Fly is 
enabled to detach its cushions from any surface to which they have been applied ; but I 
shall in due course proceed to show that this opinion is erroneous. 
Just at the base of the fifth tarsal joint, on its under surface, there is present, in Eri- 
stalis, a pair of short, very slightly curved hairs, which point almost directly downwards. 
These were first shown to me by Richard Beck ; but the discovery of their existence is so 
recent that time has not yet permitted of further search for analogous structures. In the 
instance named, they appear as if they might be little props. 
It will be best now to take into consideration the large appendages to the hands 
(fore tarsi) of the Harpalicle Beetles. These are also tenent hairs, on a comparatively 
gigantic scale : from this very fact of their size, and our consequent ability to dissect them, 
and to submit their parts to varying treatment, we shall be enabled to feel confidence 
the deductions which may be drawn from them, when applied to tenent hairs even 
of thejninutest size or the most rudimentary character. 
The largest of these appendages which I have been able to study on the living insect 
were found on the hands of a species of Eterostichits-f (fig. 20 a, PI. XLIL). Their number 
m 
* Lister; Blackwall. 
f " Latreille and De 
and 
"^ ""'"c" "us auuxaimiy lumrALiuis miu mice giuupo, hxju-ij, »»— — — 
(upon which they are chiefly founded), they term Quadrumani, Simplicimam, or -p * 
" a peculiarity in the construction of the Patellimani (Chlseniens), the males of which have the cushion-like clothin g 
of hairs on the under surface of the foot generally distributed over the sole of the tarsus In * f 
Quadrumani (Harpaliens), the dilated joints of the anterior male tarsi are furnished beneath with a double series o 
narrow cushions, which, in H. rufipes, appear to be fleshy and transversely striated, and to be destitute of p^i V 
This character, although it may be sufficient to separate the Chlseniens from the Harpali 
Feroniens : thus, in Abax #fr*» 
