272 E. T. Atkinson — On the Bomojpterous Family CoccidaB. [No. 3, 



is inclosed, there is no such secretion. In no case is the shield com- 

 posed of cast-off skins alone, and, where it appears so, closer examina- 

 tion will show the secretion. 



In the ? as in the $ , the shape and colour of the shield varies 

 with the genera and species. In Aspidiotus, Diaspis, Aonidia, and 

 Targionia, the shield is circular or oval with the first larval skin in or 

 near the middle ; in Parlatoria and Leucaspis it is produced, oval, with 

 the first larval skin at or near the apex ; in Fiorinia it is elongate and 

 with parallel sides, and in CMonaspis and Mytilaspis it is mussel-shaped. 

 Dr. Low further observes* that the shields in the ^ are smaller, nar- 

 rower, and often quite differently formed from those of the ? , so that, 

 if we find one with a single larval skin attached, this character will 

 help us to ascertain whether the insect beneath is a (? or ? , — if the 

 specimen be a ? , it must be in the last larval stage, if it be a S , it must 

 be either a larva or a pupa. In examining the ^ of the second group 

 above noticed, in which the ? is completely enveloped, care must be 

 taken not to mistake the second larval skin for a dead larva. If it 

 appears as a small thin pellicle not attached to the shield, it is a dead 

 larva, but if be a stiff, semicorneous body attached by its dorsum to the 

 first skin, it is the second larval skin and beneath is the living female. 

 The following table gives Low's arrangement of the genera of this 

 group. 



Table of Genera. 



A. Aspidiotaria : — The perfect 2 not enclosed in the second (lower) 

 larval skin, which forms a portion of the shield, and which itself is smaller 

 than the perfect shield and has a secretional appendage on its border. 



a. Shield in 2 circular or broadly oval, with the first larval skin 

 placed in or near the middle. 



a. Shield in 2 flat, plate-shaped, not closed beneath. 



1. Shield of ^ oval or ovally produced, the larval skin placed 



somewhat away from the middle : — Aspidiotus, Bouche 

 [Sign., A. S. E. F. (4 ser.) ix, p. 113, 1869]. 



2. Shield of S long with almost parallel sides, scarcely broader 



than the larval skin which is placed at its apex with 

 median and lateral longitudinal ridges : — Diaspis, Costa 

 [Sign., 1. c. 431]. 

 h. Shield of ? highly convex, hemispherical, closed beneath by a 



* Where there is difficulty in detecting the construction of the shield, the same 

 writer recommends its being dissected in a solution of caustic potash or boiling 

 water. 



