308 STATES OF INSECTS. (Imago.) 
subdivide it, and consider the sexual characters that di- 
stinguish—the Head, Trunk, and Abdomen of insects, 
and their several appendages. 
1. The Head. This part in some females is consider- 
ably larger than it is in the male. This is the case with 
the ants, and several other Hymenoptera ; while in some 
Andrene, as A. hemorrhoidalis, and Staphylinide, as 
Goerius olens, that of the male is the largest. But in 
none is the difference more conspicuous than in the stag- 
beetle (Zucanus); in which genus the male not only ex- 
ceeds the female in the length of his mandibles, but also 
greatly in the size and dimensions of his head. In the 
Apion genus, the rostrum of the female is generally 
longer and slenderer than that of her mate; and in 
Brentus, the rostrum of one sex (probably the male) is 
long and filiform, while in the other it is thick and 
short. This is particularly visible in_B. dispar and maz- 
illosus*, &c. . 
One of the most striking distinctions of the males in 
this part of their body, are those threatening horns, usu- 
ally hollow, with which the heads of many of the male 
petalocerous insects and some others are armed, and 
which give them some resemblance to many of the larger 
quadrupeds. Many are wnicorns, and have their head 
armed with only a single horn; which in some, as in 
Oryctes Illig., Dynastes Endymion, &c. is very short; in 
others, very long, as in Dynastes Enema, Pan, Megasoma 
Elephas*. In one, again, it is thick and robust; as in 
the clumsy Megasoma Actgon’: in another very slender, 
* Oliv. no. 84. Brentus, t.i. f. 1. 6. e. t. ii. f. 17. a. b. 
> Tbid. no. 3. Scarabeus, t. xviii. f. 169. 
° Ibid. Scarabeus, t. xii. f. 114. t. xv. f. 138. a. 
* Ibid. t. v. f. 33. 
