STATES OF INSECTS. (Jmago.) 333 
neither. In Pelecinus Polycerator, one of the Ichneumon 
tribe, or an insect very near it from Brazil, these thighs 
in the female are armed with two spines underneath, 
which are not in the male. : 
The anterior tibie in Scarabeus longimanus L. differ 
remarkably in the sexes. In the female they are of the 
ordinary shape, and serrated externally; but in the male 
they are very long, incurved, and without teeth or serra- 
tures?. In the males of the genus Onitzs they are bent 
like a bow, and acute at the end; but in the females they 
are formed on the common type. In Hispa spinipes 
they are armed internally with a crooked spine . But 
the most extraordinary sexual variation of this joint of 
the leg may be seen in the male of Crabro cribarius and 
several other species of the same family, in which these 
tibize are dilated externally into a concavo-convex plate, . 
or rather have one fixed td them and part of the thigh, 
of an irregular and somewhat angular shape 4, with nu- 
merous transparent dots, so as not badly to resemble a 
sieve: whence the trivial name of the species. Rolander, 
who first described it, fancied that this plate was really 
perforated, and that by means of it the animal actually 
sifted the pollen; but it is most probably for sexual 
purposes. In another species, the plate is ornamented 
with transparent converging streaks. In the bee-tribes 
(Anthophila) the posterior tibia of the working sex is 
generally bigger than the corresponding part in their 
more idle partners: this is particularly conspicuous in 
2 Oliv. n. 3. é. xxvii. f. 27. 9. and ¢. iv. f. 27. 3- 
Pelbidst, vit. 7. 08.3.2 07.2% 
© Ibid. n. 95. Hispa t. i. f. 4, Prate XXVII. Fie. 24. 
4 Pirate XV. Fie. 3. 
