18, 6 Morrison: Nondiaspine Coccidx 671 
differences which can be observed between the two are to be 
traced directly to the possible modification of shape resulting 
from the specimens settling in a position so close to the veins of 
the host. 
Key to the species of Platylecanium Cockerell and Robinson. 
a’. Antenne reduced, but plainly 4- to 6-segmented; derm clearing almost 
completely on treating with caustic potash; light brown; broad oval, 
nearly Circular. Gini a eee P. pseudexpansum (Green). 
b’. Broad oval, approaching circular in outline; antenne 1-segmented. 
P. cribrigerum (Cockerell and Robinson). 
b*. Elongate, asymmetrical, one side nearly straight, ends pointed; an- 
tenne indistinctly 2-segmented............... P. asymmetricum sp. nov. 
Genus PARALECANIUM Cockerell 
With one or two exceptions, the species of the genus Parale- 
canium now known form a compact, closely related group within 
which specific differentiation is quite difficult, particularly where 
only limited material in uncertain condition is available. On 
this account the two species which follow have been described 
with considerable reluctance, particularly the second one, where 
it has not been possible definitely to determine the nature of 
some of the structural characters. 
Paralecanium ovatum sp. nov. 
Adult female—Occurring on both sides of the leaves of the 
host, but mostly on the upper surface; flat, broad oval; maxi- 
mum length, 2.6 millimeters; width, 2; dark reddish brown, 
with a very thin, transparent coating of wax, and with two 
indistinctly marked rows of dorsal quadrate areas on each side 
_ of the middle line; some younger specimens showing a light sub- 
marginal zone similar to that described for P. zonatum (Green), 
and lighter brown in color; clearing only slightly after boiling 
in caustic potash, the older specimens remaining dark reddish 
brown; the ventral marginal zone narrow, width much less than 
half the length of anal cleft, slightly recurrent along this cleft; 
dorsal quadrate areas somewhat more distinct after boiling; 
central disk of the dorsum with only an occasional pore, outer 
two-thirds all the way around the body with numerous, obscure, 
oval or round areolations, and with an occasional clear pore; 
with a very poorly defined row of clear pores, usually in pairs, 
curving outward and forward on each side of the anal plates, 
these corresponding to the well-defined “cribriform plates” 
