20 



WILLIAM T. M. FORBES 



antennae usually have the shaft completely scaled, and the sensory 

 area confined to the club, which it may completely cover. In this case 

 there are often special areas marked by pits or grooves separated by 

 longitudinal ridges, and containing special structures. When each 



4 segment has a quadrangular exten- 



""'' -....mid .'^ s ion on the under side covered with 



these sensory hairs, the antenna is 

 called laminate or prismatic (fig. 12) ; 

 when the segments are extended side- 

 ways in little teeth, the antenna is 

 serrate (fig. 8) ; and when there are 

 long branches, it is pectinate, or, in 

 extreme cases, plumose (feathered). 

 If there is but one series of such 

 branches, it is unipectinate (a rare 

 condition) ; if there are two, it is bi- 

 pectinate (fig. 9), and when each 

 segment bears two pectinations or 

 branches in each row, it is doubly 

 bipectinate, as in the Luna moth and 

 its kin, (fig. 10). In doubly bipec- 

 tinate antennae the pectinations are 

 often alternately long and short, or 

 thick and thin. Where there is a 

 long, strong pair of bristles on each 

 segment, the antenna is ciliate or 



, ru.-uorm; o. uiuuueu aiiu uooKeu: -, , 7 j f n -\-\\ ' J.T, -L 4.1 

 6, 7, clubbed; 8, serrate and fascicu- bristled (fig. 11) ; if the bristles come 

 late, dorsal view; 9, bipectinate; 10, in distinct tufts, it IS fasciculate, but 



doubly bipectinate; 11, simple and cil- if they are numerous and scattered 

 iate; 12, laminate or prismatic, side even i y j t j s pubescent (fig. 87). 



In many sphinx moths, especially 



males, the bristles are in two vertical rows on each side of each seg- 

 ment, whose tips curve and meet so as to seem to form loops. The 

 scales on the antenna usually form two transverse rows on each seg- 

 ment (fig. 46) ; sometimes they are scattered (fig. 48) ; and in the 

 Saturniidae and many butterflies they are either wholly absent, or fugi- 

 tive, except on the two basal joints. 



The eyes vary in size and shape. Typically they are circular in 

 side view (fig. 3), and about as wide as the distance between the two 

 eyes as seen in a front view. Often the eyes are much narrower, and 

 much higher than wide (elliptical, fig. 271) or even concave on the 

 posterior margin (reniform). In the Lycaenidae they appear as if cut 



FlGS. 4-12. TYPES OF ANTENNJE 



4, Fusiform; 5, clubbed and hooked; 



