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Annals Entomological Society of America [Vol. IV, 



the length of some of the segments compared to each other. A 

 difference of only two or three microns is all that is found in 

 some of the segments. It would be exceedingly difficult to 

 eliminate inaccuracies to the extent that the formulae would 

 not ba changed by them. Or in other words, the limit of error 

 is so small that error, even with the greatest care, is bound to 

 occur. Unconsciously the measurements would be made to 

 conform to a given formula or to other measurements. The 

 writer continually met this difficulty. The measurements 

 given in Tables 6-10 were taken with an ocular micrometer at 

 a magnification of 660 diameters. Much more accurate work 

 was possible than would have been with a camera lucida. 

 TABLE 6. Pseudococcus crawii Coq. 



An examination of the tables mentioned will show the great 

 variation met with. Following herewith is a discussion of the 

 tables of each species: — 



Crawii Coq. Formula (2, 3, 8) 5, 4, 7, 6, 1, Coq. West 

 Am. -Scientist '89. 



