230 



PTILOTA : IMAGO — EXTERNAL ANATOMY. 



opposite side, or base, being occasionally prolonged into a 

 neck ; but there are numerous modifications of this form, 

 and the head is often buried as far as the eyes in the pro- 

 thoracic cavity. On minutely examining the skull, it will be 

 found that it consists of several regions. These are, the 

 epicranium or skull-cap, composing the greater part of the 

 head, of w^hich it chiefly occupies the upper and posterior 



Figs. 53, Head of Dyti 



-54, ditto Oxycheila — 55, ditto Heliocantharus — 56, ditto 

 Acantliotliorax. 



part. This is bounded in front by the clyj^eus (c), or shield 

 of the mouth, which generally lies above the parts of the 

 mouth (m), and the under side of the head is covered by the 

 jugulum, or throat. At the sides of the epicranium are situ- 

 ated the large compound eyes (e), between which, when 

 present, the ocelli (o), or simple eyes, are placed, and the 

 antennae (a) are inserted nearer to the mouth ; but all these 

 parts will require a more precise examination. 



The head is generally of a corneous, or coriaceous texture, 

 although at times it is membranous or vesiculose ; and its 

 form is modified from oval, or globose, to longitudinal, heart- 

 shaped, compressed, cornuted, rostrated, &c. The parts of 

 the epicranium, and its frontal part, the clj'jDeus, have been 

 variously regarded and named by different authors. Thus 

 Kirby and Spence divide the upper surface of the head into 

 the nose {rhinarium), hind nose {jjostnasus), forehead, crown, 

 occiput, cheeks, and temples, and the under surface into the 

 lora and jugulum ; and it is not to be denied that, in the 

 numerous modifications which occur in the form of the heads 



