1920.] 1 1 



Though I noticed one or two of tlie insects in such a situation, it was 

 evident that the slielter of the crowded adventitious l)uds was the more 

 congenial habitat, and in such a position they could he distinguislied 

 only with difficulty from the buds themselves. 



The species has recently been found on the stems of Oak trees in 

 Klchmond Park. 



Pseudococcus sphof/ni Green. 



Fresh material of Ps. sphagni, taken by Mr. Donisthorpe in the New 

 Forest, from nests of Formica picea, enables me to extend and correct 

 my earlier description of the species. 



I find that there is a distinct denticle on the inner face of each 

 claw, and that grouped spines (ceriferous tracts or " cerarii ") occur on 

 tlie two extremities of the body. These tracts are larger and more con- 

 spicuous on the anal and two preceding segments, beyond which they 

 become smaller and more difficult to detect, completely disappearing on 

 the median area, but reappearing towards the anterior extremity of the 

 body. The cerarii of the posterior series contain two spines onW, with 

 about six ceriferous pores ; those of the anterior series carry three 

 spines. A conspicuous feature of the insect is the presence of a long 

 and stout seta projecting from the lateral margins of each of tlie 

 terminal three or four segments. Smaller and less conspicuous setae are 

 situated on the same area of the other body segments. There are also 

 transverse series of longish setae across the face of each segment, and a 

 crowded group of stouter setae on the inter-antennal area. The two 

 caudal setae are considerably longer and stouter than those of the 

 anal ring. 



The insects were sent to me alive and, during their captivity, had 

 constructed well-defined ovisacs, the longest of which extended to a 

 length of 7 mm. (exclusive of the body of the insect). The ovisacs 

 were packed with pinkish eggs. 



Mr. G. F. Ferris, in a recently published paper on "The California 

 species of Mealy Bugs," makes the presence of a denticle on the face of 

 the claws a distinguishing character separating the genus Phenacoccus 

 from Pseudococcus, the latter genus being defined as " without a tooth 

 or denticle on the face of the tarsal claw." According to this specifi- 

 cation sphagni would be excluded from the genus Pseudococcus. The 

 same author characterizes the genus Phenacoccus as containing " forms 

 with not less than 18 pairs of cerarii " ; but sphagni has 12 pairs (or at 

 the most 13) — 7 in the anterior and 5 or 6 in the posterior series — and 

 would, accordingly, be debarred from a place in the genus Phenacoccus. 



