SUBFAMILY ORTHEZIINAE 109 



they coiild be applied to the groups of pilacerores when these are 

 described and used for separating the species in place of the wax 

 excreted from them. 



The ovisac is formed by the continuous band of pilacerores 

 which are located on the lateral portions of the ventral aspect. 

 The two sides converge toward the caudal end of the abdomen 

 until they meet and fuse. These plates may be known as the 

 ventral plates and the pilocerores that excrete them as the ventral 

 pilocerores. The cephalic end of the ovisac is formed by a trans- 

 verse band of pilacerores located on the first abdominal sternum. 

 Its cephalic margin is usually straight. This is why the ventral 

 surface of the ovisac is generally smooth and not fluted. The 

 transverse cephalic portion of the ovisac may be known as the 

 transverse plate and the band of pilocerores excreting it as the 

 transverse pilacerores. The two rows of plates located on the 

 dorsal aspect adjacent to each other and the meson are the dorsal 

 plates and the pilacerores that excrete them as the dorsal 

 pilacerores. They are apparently the subdorsal keels of Tinsley, 

 the subdorsal plates of Cockerell, and the dorsal or median lamellae 

 of other writers. There are typically eleven pairs of dorsal plates, 

 a row of eleven dorsal plates on each side of the meson. The 

 cephalic or first pair of dorsal plates is formed by groups of 

 pilacerores located upon the head and these may be known as the 

 head plates or the head pilacerores. They vary greatly in size and 

 shape and, when the two groups of pilacerores are continuous on the 

 head, are sometimes represented by a single plate. The tenth and 

 eleventh dorsal plates are usually very different in shape from those 

 of the other segments. They frequently form semicircular plates 

 which are continuous on the meson. The fusion of adjacent plates 

 can be indicated by the use of the word plate instead of plates as 

 when they are separate. The eleventh pair of dorsal plates is 

 located on the seventh abdominal segment cephalad of the anal 

 ring and they may be known as the preanal plates. The tenth 

 pair of dorsal plates are located on the sixth abdominal segment 

 and may be known as the paranal plates. The tube of wax sur- 

 rounding the anus is not excreted by pilacerores but by the cerores 

 of the anal ring. An examination of this wax will show that it is 

 different in structure and appearance from that execreted from the 

 pilacerores, as the wax of the dorsal plates. This tube of wax may 

 be known as the anal plate. 



A few species have plates of wax located on the meson between 

 the dorsal plates. They are generally designated as the wedge- 



