166 
some, in others slightly widening backward and rounded at the tip. 
The transverse sutures are faintly perceptible. The eyes appear as 
minute black dots, one on each side of the anterior end. The antennae 
are thread-like, and only one-fourth the length of the body. When 
highly magnified, they appear to be four jointed, the joints twice as 
long as thick, the first joint cylindrical, the two following ones thicker 
toward their tips, and the last one slightly longer than the others, and 
thickest toward its base. The feet are but one-jointed, half as long as 
the shanks, and end in a pair of hooks. 
The ‘mature lice are 0.08 long, their width less than half their length, 
some being much broader than others. They are oval, and of a 
dull white color, with the legs, antennae and beak dusky, sometimes 
pale smoky with their bases nearly white, and in other specimens 
much darker and even blackish their entire length, with the end of 
the body also slightly. The beak is appressed to the breast appearing 
like a short dusky mark upon the skin, its tip scarcely reaching the 
base of the second pair of legs. The antennae are shorter and more 
slender than the fore legs, thread-like and five-jointed, the joints cylin¬ 
drical. The two basal joints are slightly thicker than the following ones, 
and their length double their thickness. The third joint is variable in 
its length, in the mature females being almost double the length of 
the second, and but little shorter than the last joint, whilst in the 
narrower younger lice it is little, if at all, longer than the second. 
The fourth joint is the shortest of all, being but little longer than 
thick. The last joint is longest, and is bluntly rounded at its end. 
The sutures of the body are marked by slender impressed transverse 
lines. The feet show but one distinct joint, which is cylindrical, and 
four times as long as thick in the hind pair, shorter in the middle and 
anterior pair, with two hooks at the end. 
On the roots of lettuce, often in great numbers; very small oval, 
white and pale-yellow lice, with dusky legs and antennae, their bodies 
dusted over with a white powder. 
Rhizobius po^e. n. sp. 
This singular species is placed in Rhizobius , although in some re¬ 
spects it differs from this genus as understood by Passerini. 
Wingless viviparouz female .—Size small, the length about .05 inch, 
width at widest point about two thirds the length; reguarlarly ellipti¬ 
cal in outline, very convex, a cross section at any point presenting 
almost a circle; covered with a blueish white powder, but when this 
is removed, of a reddish brown, or brownish flesh color. Legs very 
small and very short, the pairs rather distinct from each other; the 
tarsi apparently but one jointed when examined carefully under a 
strong power. Antennae apparently seven-jointed, very short, and not 
tapering, the last joint being as thick as the preceding and maintain¬ 
ing this thickness to its tip; first joint very thick, its length about 
equal to its diameter; second joint about the same length or very 
slightly longer, diameter not more than half that of the first and not 
exceeding that of the remaining joints; third joint shortest, not more 
