ART. 12. MASKELL GENERA OF COCCrDAE MORRISON. 13 



locular disk pores with simple centers ; derm with a few fairly short, 

 stout setae, the circular chitinized disk at apex of abdomen bearing a 

 pair of large setae, and a number of smaller threadlike setae; 

 anal tube large and stout, bearing a single circle of clear pores a little 

 nearer inner than outer end, and a band of irregular wax plate pores 

 about three deep at inner end ; no ventral cicatrices observed. 



Larva. — Oval, somewhat narowed behind; antennae 6-segmented, 

 short and stout, the club not especially conspicuous; legs normal, 

 but rather short and stout, claw with denticle and slender somewhat 

 knobbed digitules; mentum long triangular, 2-segmented; with two 

 pairs of thoracic spiracles, with chitinous bar attached, and presum- 

 ably with seven pairs of abdominal spiracles, these much smaller 

 and simple; derm with rather numerous disk pores with the loculi 

 varying from two to four, and with fewer clear pores ; derm setae not 

 numerous, fairly large, but slender; posterior apex of body with a 

 circular chitinized area bearing a pair of long apical setae, a number 

 of long slender, thread-like setae, slightly knobbed at tips, and a 

 number of clear pores; anal tube well developed, opening in the 

 middle of this chitinous area, long, striate longitudinally, with a 

 single circle of cylindrical pores nearer inner end than outer, and a 

 double collar of wax pores at inner end. 



If it were not for Maskell's extended description of the habits and 

 appearance of the adult of this insect, there would be some doubt as 

 to whether the stage described by him was really adult. As was 

 noted in the body of the description, the legs, although greatly re- 

 duced, are present in both of the late stages of the female examined, 

 and the genus is therefore based on a morphological inaccuracy. The 

 practical loss of the legs, together with some other structural modi- 

 fications, seems to give sufficient grounds for the retention of the 

 genus as a valid zoological unit. In this connection, mention may be 

 made of a Japanese species, Xylococcus alni Oguma {not X. alni 

 Florence), recently described in detail by Oguma,* which is said to 

 have the legs entirely wanting and the antennae reduced to one- 

 segmented stubs in the adult female, and which may prove on com- 

 parative study to be related to U. asshnile (Maskell). 



The generic diagnosis following is based wholly on the type 

 species. 



GENEEIC DIAGNOSIS OF rLTRACOELOSTOMA. 



Coccids belonging to the Monophlebine-Margarodine series; adult 

 female enclosed in a heavy test placed in the twig axils of the host; 

 nearly globular, antennae and legs very much reduced, the first 

 5-segmented; mouth parts wanting; with 7 pairs of abdominal and 

 two pairs of differentiated thoracic spiracles, all without pores; 



* Jour. Col. Agr. Hokkaido Imp. Univ., Sapporo, Japan, toI. 8, pt. 3, Mar. 1919, pp. 

 77-109. 



