676 EXTERNAL ANATOMY OF INSECTS. 
that the generality of insects (for all have not these 
organs) have really a didactyle or tridactyle hand or 
foot; and the hypothesis so often alluded to—that the 
cubitus or tibia, &c., is really analogous to the carpus or 
tarsus in vertebrate animals *#—seems to receive no small 
confirmation from it; since, if the spurs be really ana- 
logous to fingers or toes, the part they articulate with 
cannot be the ¢zbza, &c. Though the parts in question 
did not escape the notice of Reaumur, Linné, De Geer, 
Latreille, &c., yet they have not been employed in the 
determination of tribes, genera, &c., except by the author 
last named, but perhapsadopted from Bonelli’, in the sub- 
genera Sabrus and Pelorus : in many instances, however, 
they afford excellent subsidiary characters, sometimes 
common to a whole Order, and at others distinguishing 
its various subdivisions. With regard to their number 
—I have noticed many variations which I will now state 
to you, first observing that I shall express them by three 
figures, the rst representing the number of spurs on the 
anterior leg, the second that of those on the zntermediate, 
and the third on the posterior ; and where there are 
spurs, as in the TVrichoptera and Lepidoptera, on the 
middle as well as at the end of the ¢zbia, I shall express 
it by one figure over another, the upper one representing 
the number of the middle spurs. If you make an ex- 
amination yourself, it will be proper to remind you that 
these little organs are extremely liable to be broken off, 
but the socket in which they were planted is usually very 
visible. ‘The most natural number is represented by 
* See above, p. 589, 661. &c.  » Régne Animal, iii. 191. I have 
never had an opportunity to consult Bonelli’s Observ. Entomolog. on 
the genus Carabus L. in the Memoirs of the Turin Academy. 
