2 GENKRA OF HYMEXOPTKRA. 



The Head (fig. 1, front view) is generally transverse and nar- 

 rower, rarely wider, than the thorax, and varies greatly in form, 

 being sometimes globose, quadrate or elongate, with all the gradations 

 from one to the other ; it is frequently more or less extended behind 

 the eyes ; the vertex or crown is the highest part, on which the sim- 

 "^ pie eyes or ocelli (e) are placed, back of it is the occiput ; anterior to 



the ocelli is the front or face upon which the antenna> are inserted, 

 while back of the eyes are the cheeks which are sometimes niv/re or 

 less inflated, and very rarely dentate. The eyes (a) are generally 

 large and lateral, naked, rarely pilose, occasionally occupying in the 

 males of certain groups, tiie greatest portion of the head ; they vary 

 much in form and size, being sometimes reniform, ovate or circular, 

 sometimes small or even minute and very rarely wanting ; they are 

 accompanied by three small simple ocelli (e) placed either in a tri- 

 angle or 1 a straight or curved line upcm the vertex, but in the 

 apterous females of certain genera of Heterogyna and Mutillidae 



these ocelli are entirely wanting, while in 

 some of the Larridae and Sapygidte, the j)03- 

 terior pair is distorted and subobsolete ; oc- 

 casionally, as in Ophion, they are unusually 

 large and prominent. The dypeuH (b) is 

 placed on the front, beneath the insertion of 

 the antenna; (f) and is variously formed, 

 usually shield-like, but often narrow and 

 transverse, and sometimes produced into va- 

 p- J rious curious shapes, the apical margin being 



a, eyes ; b, ciypeus ; c, lab- often denticulate; in the Dorylida; it is very 

 rum;d, mandibles; e, ocelli; niiuute or obsolete. The mandible'* or jaws 



f, insertion of antennte. , ,. . .11 ^i ^i 1 1 



(d) are mserted beneath tlie eyes and on each 

 side of the mouth opening, rarely contiguous at their base ; they 

 vary much in form and size, and are simple or more or less dentate 

 on their inner margin and apex, sometimes they are long and sickle- 

 shaped. The Inbrum, or roof of the mouth (c), is variously shaped, 

 transverse, ovate, cuneiform, or rostriform, and is situate in front of 

 the clyi)eus and between the mand'bles, and is often concealed by 

 them. The inner parts of the mouth, which reach the fullest de- 

 velopment in the Bees, are, in short, composed of a pair of long 

 membranous or coriaceous maxillae, each provided with a palpus 

 varying in the number of joints from 1-6, and a lower lip or tongue, 

 having a basal mentuni from which proceeds the labium and its 



