168 AULACASPIS (DTASPIS) 



natural one, as a glance at the illustrations of the 

 pygidia (PL XVI, figs. 13; PL XVII, figs. 2, 3) 

 will show. I have already dealt with Diaspis, so that 

 I need not again refer to that genus more than to say 

 that D. boisduvalii and D. bromelw may be considered 

 typical of the genus. The remaining British species 

 in Cockerell's division is Aulacaspis (Diaspis) rosae, 

 and I have added A. pentayona. A careful study of 

 these convinces me that their relation is with Ghio- 

 naspis and Poliaspis. In the general character of the 

 pygidium they closely resemble the latter, especially 

 in the form and arrangement of the dorsal tubular 

 spinnerets. These organs have hitherto received but 

 little attention, but I feel confident they are quite as 

 important as the grouped circumgenital glands which 

 have played so great a part in the separation of species. 



The species may be separated by the following 

 characters : 



A. Pygidium with five groups of circumgenital glands. 



a. Lateral groups almost continuous; median lobes 



with inner margins only free. 



(i) .... Ros^:. 



b. Lateral groups well separated ; median lobes with 



both margins free. 



(n) .... PENTAGONA. 



AULACASPJS (DiASPIs) ROS^E (Bouclic). 



(PL XIV, figs. 113 ; PL XVII, fig. 2 ; PL XVIII, 



figs. 5, 7.) 



Aspidiotus rosas, Bouche ; Naturgesch. d. schadl. und 

 niitzl., Garten-Insecten, p. 83, 2, 1833 ; id., 

 Nat. der Insecten, p. 14, 2, pi. i, fig. 6, 1834. 



Diaspis rosae- (Sandberg), Signoret; Essai, p. 123, 

 pi. v, figs. 3 et 3 a. 



