100 ASPIDIOTUS OSTRE^FOEMIS. 



beneath the thin epidermal layer of the wood (PL V, 

 fig. 3). The examples before me on plum (J*ritnn# 

 domextica) have formed a complete homogeneous layer, 

 only recognisable from the bark by the numerous, 

 minute, orange-coloured specks of the larval exuviae. 

 On removing this mass the bark appears quite white 

 from the numerous powdery ventral scales which 

 adhere to it. 



Diam. 1 2 mm. 



Adult female short ovate, almost circular, old speci- 

 mens becoming chitinised ; yellow or ochreous yellow. 

 Parasitised examples (PI. V, fig. 5) broadly pyriform, 

 inflated, usually bright orange brown, and highly 

 chitinised. Rudimentary antennas a mere stump with 

 a long stiff spine at the base. Rostral filaments 

 scarcely longer than men turn. Free abdominal seg- 

 ments, and margin in front with a few long hairs. 

 Pygidium (PL VII, fig. 2) always with five groups of 

 circumgenital glands, the anterior group consisting of 

 from 5 to 8, the anterior laterals from 7 to 12, the 

 posterior laterals from 5 to 1G. The formula of twelve 

 examples from a single colony on plum are given 

 below : 



57 5 6 56 



810 . 910 . 8 7 . 7 8 . 9 9 . 67 

 8_10 . 9 8 . 5- 6 . 1011 . 11-- 9 . 1211 



655 8 65 



11 7 . 910 . 711 . 8 8 . 1212 . 9 9 

 8_ 8 . 811 . 1613 . 1211 . 1114 . 11-- 9 



The subdorsal groups of tubular spinnerets, rather 

 short, are connected with a double series of glands or 

 pores. Extending from near the last marginal spine 

 to the base of the pygidinm on the dor sum is a series 

 of, usually four, large circular pores. Vaginal opening 

 central. Anal opening about midway between the 

 former and the apex of the pygidium. Margin of 

 pygidium (PL XII, fig. 1) with two pairs of lobes; 

 median pair well developed, rounded, and notched at 



