1912] North American Scoliine 303 
The metapleuron extends downward and backward from the 
base of the posterior wings. Half-way between the base of the 
wings and the base of the metacoxa the plate narrows and appears 
to be separated into two parts by a transverse furrow. The 
upper part is very near the shape of a triangle, with one side, 
the hinder one, rounded. The lower part continues downward 
and backward between the edges of the median segment behind 
and the mesopleuron in front forming the posterior part of the 
mesocoxal cavity, the upper and anterior parts of the metacoxal 
cavity and passing between the two coxal cavities to unite with 
the metasternum though there is no trace of the suture between 
these two plates. Both parts of the metapleuron are more or 
less coarsely punctured and hairy. The metasternum extends 
backward from the mesosternum between the meso and meta 
coxee, its sides in part forming the ventral edges of the coxal 
cavities and the apparent posterior margin is free. This part 
of the metasternum is only sparsely punctured and covered 
with hairs while its shape varies. It has a median groove 
extending forward from the apparent hinder margin for a 
varying distance. This apparent hinder margin is not the real 
one, however, the plate turning backward on itself for a short 
distance, then bending at right angles and passing dorsalward, 
thus forming a backward projecting flange. The vertical por- 
tion is bilobed and at its dorsal magrin (the real posterior 
margin of the plate) articulates with the sternal plate of the 
petiolar segment. This flange is covered with coarse punc- 
tures and long coarse hair. 
MEDIAN SEGMENT. The median segment is really the first 
segment of the abdomen which has become closely connected 
‘with the thorax and has often been considered one of the seg- 
ments of this division. It is followed by the petiole, a con- 
stricted portion which extends backward and suddenly enlarges 
to the regular size of the abdominal segments. For any mor- 
phological consideration this arrangement should be remembered 
but for convenience in this paper the petiole with its enlarged 
portion is considered the first segment of the abdomen. 
Viewed from above the median segment appears to be 
composed of a central portion and a lateral portion on each 
side, the separation of these parts being indicated by a depressed 
line or shallow groove arising at the front margin of the plate 
nearly opposite the point where the central elevated part of the 
