HOMOPTERA 



445 



tures, using the terms that are more generally applied to them. 



The anal ring. — In the mealy-bugs, the tortoise-scales, and the 

 lac-insects, and in the nymphs of some others, the anus is 

 surrounded by a well-defined ring, the anal ring (Fig. 517, r). 



The anal-ring setce. — The anal ring bears several, from two to 

 thirty but usually six, long and stout setae, the anal-ring setce (Fig. 



517.^)- 



The anal lobes. — 'In many coccids, the caudal end of the body is 

 terminated by a pair of lobes, the anal lobes (Fig. 517, /). 



The anal setce. — Each anal lobe bears one or more prominent setae, 

 the anal setce (Fig. 517, as). 



The anal plates. — In the subfamily Lecaniinse, the abdomen of 

 the female is cleft at the caudal end, and, at the cephalic end of the 

 cleft, there is a pair of tri- 

 angular, or sometimes semi-cir- 

 cular plates, the anal plates 

 (Fig. 518, ap). 



The pygidium. — In the sub- 

 family Diaspidinae, the abdo- 

 men of the adult female is ter- 

 minated by a strongly chi- 

 tinizedunsegmented region, 

 which consists of four co- 

 alesced segments (Fig. 519); 

 this region is termed the pygid- 

 ium by writers on the Coccidae. 

 This application of the term 

 pygidium is quite different 

 from that used in descriptions 

 of other insects, where it refers 

 only to the tergite of the last 

 abdominal segment. A more 

 detailed account of the charac- 

 ters presented by the pygidium 

 ofthe Diaspidinae isgiven later. 



The spines and the setce. — -The position and number of spines and 

 of setae are often indicated in specific descriptions. Care should be 

 taken to distinguish between these two kinds of structures. A seta 

 can be recognized by the cup-like cavity in the cuticula, the alveolus, 

 within which it is jointed to the body; while a spine is an outgrowth 

 of the cuticula that is not separated from it by a joint. See figure 42, 

 page 32. The writer in his early works on the Coccidae ('81, '82, '83) 

 termed certain spine-like setae spines. 



The outlets of wax-glands. — In the Coccidae there are many minute 

 openings in the cuticula through which wax is excreted; these vary 

 greatly in form, in position on the body, and in the structure of the 

 part of the cuticula through which they open. As the characters 

 presented by these openings are much used in the classification of 

 coccids, a very elaborate terminology referring to them has been 

 developed. Unfortunately different authors use quite different terms, 



Fig. 518.— A 



Lecanium, 

 enlarged : c^, 

 anal plates. 



Fig. 519. — Adult female 

 Lepidosaphes: p, py- 

 gidium. 



