\\ \ h\n \\i> i-i! 



easily re< o^ni/ed lii, h the upper lip. 



is hinged, though llic clypeUfl Ifl n<>t invariably delimited Rfl a di 



iderite. In certain iture divides tin- lypeus 



into an <inlc<lyf>cns and a f>o.\l<lyf><'i<\. 'I IK- < li 



known a> the i;r;/rf, and />^>.s/ ;v;/r/' M.metii: :. On theiindr 



of tin- head is the gnlii, which l>ear> the under lip, or Itibium. 'I'hat part 



of the skull nearest the prothoiax i- termed the occiput; usually it i 



delimited from tin- epicranium, though in MOT ntinuous 



with the post-^ena- to form a distinct M lerite. The occiput surrounds 



the opening known as the occipital foramen , through which the 



oc 



PIG. 34. Skull of a grasshopper, Melanoplus differentialis. a, antenna; c t clypeus; e, 

 compound eye; /, front; g, gena; I, labrum; Ip, labial palpus; m, mandible; mp, maxillary 

 palpus; o, ocelli; oc, occiput; pg, post-gena; v, vertex. 



gus and other organs pass into the thorax. The membrane of the 

 neck in Orthoptera and some other insects contains small ccr 

 sclerites, dorsal, lateral or ventral in position^ these, in the opinion of 

 Comstock, pertain to the last segment of the head. Besides those 

 described, a few other cephalic sclerites may occur, small and incon- 

 spicuous, but nevertheless of morphological importance; for example, 

 ocular or antennal sclerites, bearing the eyes or the antennae, respec- 

 tively; and the trochantin of the mandible, situated between the mandi- 

 ble and gena. 



Tentorium. In the head is a chitinous supporting structure known 

 as the tentorium. This consists of a central plate from which diverge 

 either two or three pairs of arms (anterior, posterior amid or sal] extending 



