viii 



INTRODUCTION. 



HEAD, caput. Figs. 3 to 7. 

 .Fig. 3. 



The head is located in front of the thorax and separated from it, 

 in most instances, by a very indistinct segment. On both sides 

 are situated the large globular reticulated eyes, oculi, b ; between 

 them and above is the vertex, c ; in front is the frons, d ; and be- 

 low at the end is the mouth, os. The orbits of the eyes, orbita, fig. 

 4, e, are often distinguished by color and the character of the 

 scales. Between the vertex and frons are the feelers, antenna, a, 

 near the eyes, behind them at the orbita, or at a little distance from 

 them in many species, are two small, round, smooth elevations, 

 which are called simple eyes, ocelli, f. 



The parts of the mouth are but little developed in butterflies. 

 The proboscis or tongue, lingua, g, is composed of the two lower 

 jaws (maxillce} grown together as a double tube and usually sepa- 

 rated only at the end, and which, for the most part, is corneous and 

 spiral. It is seldom absent, or consists only of two slender, soft 

 threads. Under the tongue are placed the two palpi, h, which are 

 three jointed ; above these in many nocturnal moths there are in 

 addition two palpuli, figs. 5 and 6, i. The palpi are of various 



form and size, sometimes scarcely visible, sometimes as long as the 

 head and thorax together; the scales on the palpi are also of vari- 

 ous density; the second joint is usually the longest and most 

 densely scaled, the terminal joint is, for the most part, slender and 

 pointed, frequently setaceous. 



