Maskell. — On Coccidae. 73 



insect absolutely, in its adult state, devoid of any visible 

 organs, except its rostrum and setas, and yet it is precisely in 

 that adult state that it works its way deep into hard wood 

 and digs out a cavern for itself. Before impregnation by the 

 male it lies scarcely buried by the outer bark of a twig ; at 

 gestation it is found deep down in the wood. It is, of course, 

 easy enough to say that the thing must be done "by some 

 chemical action ' ' ; but what action ? what chemical product ? 

 what secreting organ exists for the purpose ? 



EXPLANATION OF PLATES I.-VII. 

 Plate I. 

 Aspidiotus ceratus, pygidium of female. 

 Aspidiotus vitiensis, pygidium of female. 

 Aspidiotus unilobis, pygidium of female. 

 Aspidiotus extcnsus, adult female, dorsal view. 



pygidium of female. 

 Aonidia fusca, insects on twig. 



„ puparia, female and male. 



diagram showing adult female smaller than se- 

 cond pellicle. 

 „ pygidium of female. 



Mytilaspis nivea, pygidium of female. 

 Mytilaspis striata, puparia, female and male. 

 „ pygidium of female. 



Plate II. 

 Mytilaspis lactea, puparia, female and male. 



pygidium of female. 

 Chionaspis prunicola, puparia, female and male. 

 „ adult female, dorsal view. 



„ pygidium of female. 



Chionaspis xerotidis, insects on plant. 



„ puparia, female and male. 



Fiorinia expansa, insects on twig. 



„ insects on leaf, enlarged. 



diagram of arrangement : a, larval pellicle and 

 threads ; b, second pellicle ; c, adult female ; 

 d, fibrous secretion, 

 puparium of male. 

 „ pygidium of female. 



„ second pellicle. 



Plate III. 

 Ctenochiton eucalypti, insects on leaf. 



tests of female, dorsal view. 



test of female, side view. 



test of male, dorsal view. 



antenna of female. 



foot of female. 



spiracular spines of female. 

 „ female, second stage, dorsal view. 



„ larva. 



antenna of larva. 

 „ foot of larva. 



„ abdominal spike of male. 



