686 EXTERNAL ANATOMY OF INSECTS. 
comparing the three pairs of this joint with each other, 
the most general rule is, that the anterior should be the 
shortest, and the posterior the longest : but in some, as 
the Capricorn beetles, &c., they are nearly equal in 
length; in others, as Cantharis marginata, the anterior 
pair, and in Rhzpiphorus the intermediate, are the long- 
est; in Trichius Delia these last are the shortest. With 
respect to thickness, the anterior tarsz, except In many 
males *, are not very strikingly different from the rest. 
With regard to the proportion of the joints of the 
tarsus to each other,—according to the most general law, 
the first is the longest, the last next in length, then the 
second and third, and the fourth is the shortest. In 
Gonyleptes and other Phalangide the first is almost 
thrice the length of all the rest taken together; but there 
are numerous exceptions to the rule. In the female 
Carabi the first joint is not longer than the last, and in 
the males not so long; and in Hydrophilus, &c., it is the 
shortest of all. Again, the second joint is longer than 
the three following ones in Dasytes ater»; and than the 
last in Cicindela sylvatica: the third joint is shorter than 
the fourth in Lampyris ignita: it is longer than the first 
in Donacia, many Melolonthide, &c. Once more, the 
fourth joint, usually the shortest of all, is longer than the 
second and third in Anthia, &c.. Lastly, the claw-joint, 
usually the second in length, in the Hproboscidea is very 
long and large, while the four first joints are so extremely 
short as to be scarcely distinguishable from each other : 
it is the shortest of all in Colymbetes, &c.; it is of the 
length of the third in Cicindela sylvatica, of the fourth in 
* See above, p. 334—. > Prate XXVII. Fic. 25. 
