EXTERNAL ANATOMY OF INSECTS. 677 



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 a — 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 tibia, &c. Though the parts in ques- 

 tion did not escape the notice of Reaumur, Linne, De 

 Geer, Latreille, &c, yet they have not been employed 

 in the determination of tribes, genera, &c, except by the 

 author last named, but perhaps adopted from -Bonelli b , 

 in the subgenera Zabrus and Pelorus : in many instances, 

 however, they afford excellent subsidiary characters, 

 sometimes common to a whole Order, and at others di- 

 stinguishing 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, thefirst representing the number of spurs 

 on the anterior leg, the second that of those on the inter- 

 mediate, and the third on the posterior ,• and where there 

 are spurs, as in the Trichoptera and Lepidoptera, on the 

 middle as well as at the end of the tibia, I shall express it 

 by one figure over another, the upper one representing the 

 number of the middle spurs. If you make an examina- 

 tion 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 2:2:2; this 



a See above, p. 591, 667, &c. b Regne Animal, hi. 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. 



