90 



ANATOMY OF AN AftTHEOPOD. 



32 A, c), a broad plate, which is followed by a smaller plate united 

 to the front of the clypeus, called the labrum or "upper lip" 

 {L). The plate on each side below and behind the eyes is called 

 the gena or cheek (G). Ocelli are absent in this type, other- 

 wise they would be situated on the epicranium. The thorax 



Fig. 31. — Structure of an Arthropod {Periplaneta wmeHcarm). 



Hf head; Th, thorax; Ab, abdomen; Mxp, maxillary palps; Zp, labial palps; Jlf, 

 maxillse ; Antf antennae ; E, eyes ; Ep, epicranium ; /, fenestrEe ; P, prothorax ; M, 

 mesothorax; Jlfe.meta thorax; Ce, cerci; S, styles; Mw and Mew, meso- and meta- 

 thoracic wings ; PZ, Af.Z, and Me.lj legs ; Fe, femur ; Ti, tibia ; Tr^ tarsus ; 1-10, abdom- 

 inal segments. 



is composed of three segments, united by sutures. Each seg- 

 ment is known respectively as the pro-, meso-, and metathorax 

 (fig. 31, Th). The tergum or pronotum, the upper portion, is 

 prolonged over the neck. The mesothorax, which is smaller 

 than the prothorax, bears a pair of leathery wings. These 



