SUBFAMILY DIASPIDINAE 237 



17-21 

 8-13 



24-24 Or 6X5 Or 



15-17 2X2 



These translated into the form just given, would be: 14(24-24) 

 15-17 or 3(5-6)2-2 or (17-21)8-13. The most intricate formulae 

 are those used by Lindinger. The following are a few samples 

 translated in each case to the form given in the preceding para- 

 graph : 5-9 : 5-10 : 5-7 : 5-10 : 5-9 equals 5-7 (5-10) 5-9 ; 23 : 27 : 19 : 

 32: 19 equals 19(27-32)19-23; 1-4: 1-4: 0: 1-4: 1-4 equals (1-4) 

 1-4; 0: 0-2: 0-2: equals 0(0-2)0; 10: 11 10: 9: 8; 4: 10: 8: 

 7: 9; 10: 18: 11: 15: 10 equals 10(9-11)8-10 and 8(7-10)4-9 and 

 11(15-18)10-10. The last formula is to show the number in 

 three individuals. If colons have been accidentlly substituted 

 for the semicolons in the printing, as sometimes happens, there is 

 difficulty in the interpretation of the formula unless one is famil- 

 iar with the underlying principal of the construction of the for- 

 mula. Each formula is apparently to consist of five groups of 

 numbers separated by colons, a group of numbers for each group 

 of genacerores, and the second five groups of numbers, whether 

 separated by a semicolon from the first five groups or not, repre- 

 sents another individual and is a different formula. 



The mesogenacerores usually have fewer cerores than either 

 of the other groups and are frequently wanting or represented 

 by one or two cerores. They sometimes combine with the pre- 

 genacerores and form a single large crescentic cephalic group. 

 Such a group is known as a solaceroris. The postgenacerores 

 being distinct, in such cases, the pygidium is said to have three 

 groups of genacerores. The pregenacerores and the postgena- 

 cerores sometimes combine forming a single elongate group on 

 each side of the vulva. The group of each side is known as a 

 latagenaceroris. The pygidium in such cases is said to have three 

 groups of genacerores if the mesogenacerores are present and 

 two if they are wanting. In a few cases the genacerores form 

 a large U-shaped group, from their form evidently arising from 

 a fusion of all five groups of genacerores, the omnagenaceroris. 

 "When two or more groups of genacerores combine or fuse they are 

 sometimes described as genacerores confluent. There are in cer- 

 tain genera as Poliaspis, more than five groups of genacerores 

 present. In certain species of this genus, as media Maskell and 

 cycadis Comstock, the three extra groups of genacerores appear 

 to be groups of cerores of the abdominal segments cephalad of 

 the one bearing the mesogenacerores. In other species the extra 

 groups appear to have been formed by the subdivision of some 



