EXTERNAL ANATOMY OF INSECTS. 477 
the face by two elevated lines, forming nearly a triangle 
and bounded by the horn. Or take a common wasp or 
hornet, and you will find a similar space, though ap- 
proaching to a quadrangular figure, marked out by zm- 
pressed lines», In Leptis and Sciara, two Dipterous ge- 
nera, this impression is so deep as to look like a suture. 
Between these lines, in those cases, is included what I 
call the nose. As to substance, in general it does not dif- 
fer from the rest of the head; but in the Cleride it is al- 
most membranous. You must observe, that in all these, 
what at first sight appears to be the termination of the 
front, is not the nose, but the narrow depressed piece 
that intervenes between it and the lip. With regard to 
its clothing, it is most commonly naked, but in some 
genera it is covered with hair; in Crabro often with 
golden or silver pile, which imparts a singular brilliance 
to the mouth of the insects of that genus: M. Latreille 
supposes that the brilliant colours of the golden-wasp 
(Chrysis) may dazzle their enemies, and so promote their 
escape*; the brilliance of the mouth of the Crabro may 
on the contrary at first dazzle their prey for a moment, 
so as to prevent their escape. ‘The ,form of the nose, 
where distinct from the rest of the face, admits of seve- 
ral variations ; thus in the Staphylinide and Clerid@ it 
is transverse and linear; in Copris it is triangular, with 
the vertex of the triangle truncated ; in Vespa Crabro it 
is subquadrate and sinuated. In many Heteromerous 
beetles’ it is rounded posteriorly: in a new genus in 
* Prate XXVII. Fic. 4. a. > Prate VII. Fie, 2. a. 
* Observ. Nouv. sur les Hyménoptéres (Ann. du Mus.) 5. 
* Those beetles whose posterior pair of tarsi have only four joints 
and the two anterior five, are so called. 
