158 THE COCCIDAE 



are typical in form with a slender pointed flexible shaft, in others 

 the shaft is stiff and inflexible or spine-like. The distal portion of 

 the shaft is frequently distinctly enlarged or dilated forming a 

 clavate seta. Such setae may have the clavate distal portion of 

 the shaft indented or toothed forming frayed or furcate setae. 

 The marginal setae in certain genera have been modified into 

 flattened scales which are broad oval in outline or almost round, 

 broader than long. They differ from the lepidopterous scales in 

 their uniformly convex untoothed margin. They are designated 

 as flabellae by Green and as flabelliform marginal hairs by others. 



There is on the dorsal aspect of certain species a varying 

 number of small tubercles, ten to twenty, which have been described 

 and figured by both Thro and Green. They were named sub- 

 marginal tubercles by the latter, who considered them as glandular 

 in nature. There are usually about five on each side of the body 

 near the lateral margin. Thro describes in one species a mesal row 

 of twenty. These minute structures rest upon the surface of the 

 cuticle and resemble in profile a small neckless flask with a central 

 dipper. Since they are likely to occur upon any part of the 

 dorsum, they have been named the dorsal tubercles. 



The caudal extent of the head can not be determined. The 

 eyes are usually inconspicuous or wanting, when present they are 

 small, slightly convex areas which are sometimes darkened with 

 pigment and located on each lateral part of the ventral aspect of 

 the head. 



The antennae usually consist of six to eight segments. This 

 number may be greatly reduced or the antennae modified into 

 mere tubercles, while in certain genera the antennae are always 

 wanting. In some genera the length of the segments is greatly 

 reduced and the antennae as a whole greatly shortened, while the 

 typical number of segments may be present. The comparative 

 length of the segments of the antennae, expressed in the form of 

 a formula, has been used by certain workers in differentiating 

 species. Such characters are no more reliable here than in the 

 other subfamilies. This fact and the general uniformity of the 

 number and arrangement of the antennal setae has been noted by 

 Thro, who found the number identical in the different species that 

 he studied and in cases noted where there was a difference and he 

 was able to find material for study, found that some of the setae 

 had been broken off and overlooked. The interantennal setae are 



