338 STATES OF INSECTS. (Jmago.) 
In general shape it often differs in the sexes. Thus, 
the abdomen of female T7pule is lanceolate; that of the 
male cylindrical, and thickest at the extremity*. In 
Molorchus it is convex above in the former, and flat in 
the latter,—the female of this beetle not unaptly repre- 
senting some female Ichneumons in this respect, and the 
male their males>. In Andrena it is oblong in the one, 
and lanceolate in the other. In the hive-bee the drones 
have a thick, obtuse, and rather long abdomen; in the 
females it is long, and nearly represents an inverted cone ; 
and in the workers a three-sided figure, or prism. 
The number of segments, also, is generally different 
in the two sexes—the male having one more than the fe- 
male; but in Dytiscus marginalis, &c. the reverse of this 
takes place: the female, if you reckon the bipartite half- 
concealed anal segment as one, having seven ventral seg- 
ments, and the male only six. She has also eight dorsal, 
and the male seven.—In the ant tribes (Formica L.), the 
little vertical scale, at the base of the abdomen in one 
description of them, or the double knot in another, is 
less in the male than in the female. In a very singular 
male insect belonging to the Vespzda, and related to Sy- 
nagris, (which I purchased from the late Mr. Drury’s ca- 
binet,) the second ventral segment sends forth from its 
disk two remarkable parallel very acute and rather long 
spines. ‘The same sex of Chelostoma mazillosa has like- 
wise on the same segment a concave elevation, opposite 
to which on the fifth is a cavity which receives it, when 
the animal rolls itself up to take its repose*. In another 
* De Geer vi. ¢. xviii. f. 12, 13. > Ibid. v. 151—. 
© Mon. Ap. Angl. i. 177. t. ix. Apis **, c. 2. y. f. 11. a, d. 
