666 EXTERNAL ANATOMY OF INSECTS. 
animals. With regard to the articulation of this part 
with the trochanter, it has been sufficiently explained 
under that head, and that with the ¢7dza I shall treat of 
when I come to that joint. As to the size of the thighs, 
and their relative proportions to each other and to the 
remaining joints of the leg, the most general law is, that 
the anterior pair shall be the shortest and smallest, and 
the posterior the longest and largest. With respect to the 
remaining articulations, most commonly the thigh is 
longer and larger than the ¢ébza, and the ¢idia than the 
tarsus. But there are numerous exceptions to both 
these rules. With respect to the frst, we may begin by 
observing that the increase of the magnitude of the thigh, 
from the anterior to the posterior pair, is usually gra- 
dual: but in many jumping insects, and likewise many 
that do not jump, the posterior pair are suddenly and dis- 
proportionally thicker than the rest». Again, in many 
insects the anterior pair are the longest and thickest, as 
in Acrocinus longimanus, Bibio, Nabis, &c.: in others, 
the intermediate exceed the rest in magnitude, as in Onitis 
Aygulus, cupreus ; Sicus flavipes, &c.: in many Lamelli- 
corns all the thighs are incrassated and nearly equal in 
size: but in some, as Ryssonotus nebulosus’, the inter- 
mediate pair are rather smaller than the rest. With 
respect to the second rule—in some, as in the male of 
Acrocinus longimanus, the anterior tibia, though more 
slender, is longer than the thigh ; in Hololepta mazil- 
losa it is longer and more dilated; in Lamia marmorata, 
or one related to it from Brazil, the zntermediate pair are 
longer; in Ateuchus gibbus and others of that tribe the 
posterior thighs are smaller than the ¢2bi@ : and, to men- 
* Vor. IT. p. 309—. » Linn, Trans. xii. t. xxi, f. 12. 
