ArT. 17. MONOPHLEBINAE AND MARGARODINAE—MORRISON. 35 
of thoracic and seven pairs of only slightly smaller abdominal spira- 
cles; derm pores of one sort, large, circular, multilocular disk with 
granular center and a single marginal circle of small loculi; derm 
setae small, slender, with light basal collar, comparatively few in 
number; anal opening a simple tube; ventral cicatrices small, numer- 
ous, circular, in transverse rows. Larva elongate oval, tapering 
somewhat anteriorly; antennae nearly contiguous, tapering, 7-seg- 
mented; legs not unusual; tarsal digitules with faint knob; beak long 
conical, 2-segmented; with two pairs of thoracic and (assumed) 
seven pairs of abdominal spiracles; derm pores of two sorts, ventral 
as in intermediate stage, dorsal somewhat suggestive of those of adult; 
body setae few, small, slender; apical pair of setae differentiated but 
inconspicuous; anal opening apical; with a single, median, posterior 
ventral cicatrix. 
This genus appears to have its proper location among the group 
including Steingelia, Matsucoccus, Stomacoccus, and Kuwania. 
The genotype and only included species is the following: 
PLATYCOELOSTOMA COMPRESSA (Maskell). 
Plate 2, fig. 2. 
Reference-—Fernald Cat. Coce. World, 1903, p. 30. 
The Maskell collection contains four slides of this species, as fol- 
lows: One of ‘antennae and feet of adult female, 1890,” two of ‘‘2nd 
stage female, 1890,” and one of “larva, 1891.’’ There are besides 4 
few unmounted specimens of the intermediate stages with No. 140. 
No other specimens have been available for study. 
Adult female.—Nothing could be added to Maskell’s description of 
the external appearance and the general morphological characters of 
the whole body, as only a portion of one adult, including fore legs, 
antennae and a very small amount of derm, is available for examina- 
tion; the derm pores apparently of one type only, multilocular disk 
with numerous loculi in the outer band and four or five in the cen- 
tral cluster, roughly circular or with more or less distinctly flattened 
outer faces opposite each of the loculi in the inner cluster; derm 
setae, so far as can be determined, of one type only; slender, not 
large, with flat circular collar at base, not abundant; no information 
regarding the spiracles, anal opening and other abdominal structures 
available. 
Intermediate stage female—General appearance as described by 
Maskell; antennae reduced to tiny tubercles, not distinctly segmented, 
but with faint indications of incomplete joints, bearing a cluster of 
setae at the apex; legs not entirely wanting, but each represented 
only by an oval area in the derm bearing clusters of pores and small 
setae (see figure); beak small, apparently 2-segmented, no traces of a 
third segment, as indicated by Maskell, observed; with two pairs of 
