Mouth appendages of Periplaneta (magnified).
A Mandible

B First maxilla
1 cardo
2 stipes
3 lacinia
4 galea
5 palp

C Right and left second maxillae fused to form the labium
1 submentum
2 mentum
3 ligula, corresponding to the lacinia
4 paraglossa, corresponding to the galea
5 palp

(From Latter.)