124 THE COCCIDAE 



cleared in caustic potash. The ventralabia is not an invaginated 

 pocket like the other labiae. 



The ventral aspect of the head frequently bears about eight 

 setae located between and caudad of the articulation of the 

 antennae. These setae are known as the interantennal setae. 

 They can usually be identified from the other setae of this region 

 by their greater size and the regularity of their arrangement. 



The mesothoracic and metathoracic spiracles are located in 

 the transverse furrows marking the position of the mesocoria and 

 metacoria. They appear in mounted specimens as hour-glass- 

 shaped structures. One end of each spiracle is smaller than the 

 other, is located in the cuticle of the body-wall, and contains a 

 small opening. This opening is the spiracle. The round plate of 

 cuticle which surrounds the spiracle is the peritreme. The re- 

 mainder of the hour-glass-shaped or funnel-shaped structure is a 

 modification of the spiracular trachea, although the entire structure 

 is generally figured and described as a spiracle. The flaring 

 structure or modification of the spiracular trachea is a cavera. 

 The abdominal spiracles are alwaj^s wanting. 



The claws, while generally simple, in a few genera bear a 

 single tooth near the middle of their ventral aspect. This is the 

 "denticle of the face of the claw" of Ferris. There is also some 

 variation in the number and form of the digitules borne hy the 

 claws. 



Tlie anal ring and the anal ring setae are typicallj' present 

 in the adult female. When absent, they are present in the nymphal 

 stages or at least in the first nymphal stage. The normal number 

 of anal ring setae is six judging from the large number of genera 

 that have this number and also from the fact that those genera 

 without, with less than, or with more than six in the adult female 

 often have six in the first nymphal stage. The number varies 

 from two to fifty or more, but is never apparently an odd number. 

 The anal ring setae can be differentiated as the cephalic, median, 

 and caudal when there are only six present. The cephalic anal 

 ring setae are those on the cephalic or dorsal portion of the anal 

 ring, depending upon the position of the ring. The anal ring is 

 usually more or less vertical in position, but may be dorsal, as 

 is frequently the case with the anus in the coccids. The closed 

 end of the anal ring in Pseudococcus which is the dorsal side, if 



