384 Introduction to Animal Morphology. 



as a sudden shower. Many larvae have spinning- 

 glands, early or late in development, as gland pouches 

 on the upper lip : these secrete threads, often around 

 sticks or foreign bodies (Oiketicus). Some Hymenop- 

 tera have a caudal sting. The colors of insects are 

 in the chitinous layer. 



The head bears the compound eyes, between and 

 in front of which is thefactes, consisting of the inter- 

 ocular region, from, and an anterior segment or cly- 

 pcus ; beneath the mouth is the gula; on each side 

 are the gcncc; behind the facies is the occiput, which 

 joins the frons at the vertex, and is attached to the 

 prothorax by the neck. The head may be received 

 into an anterior notch in the thorax (caput receptiun t> 

 or concealed by the thorax (c. oltcctum], or free (c. li- 

 bcrnm\ The single pair of antennae arise below the 

 eyes, and may be clavate, capitate, dentate, pectinate > 

 flabellate, geniculate, aristate, &c. ; between these 

 may be ocelli or single eyes. The head also carries 

 the oral organs, which consist of an azygous upper 

 lip (labium), movably jointed to the clypeus; laterally 

 there are, first, a pair of biting mandibles, hinged, and 

 moving like a pair of tongs, never palpiferous nor 

 jointed ; each has two condyles at base for articula- 

 tion with the inner wall of the gena. Behind these 

 are the maxillae, usually more delicate than the former, 

 and consisting of a transverse basis articulated to the 

 gula (cardo) ; on this is placed a stipes, which, on a 

 separate portion, or squama, bears a maxillary palp. 

 Internal to the stipes projects the mala or lamina y 

 often divided into external and internal. Still farther 

 back are the second pair of maxillae, rarely remaining 

 separate, usually united mesially as a lower lip 



