3°6 
The Ohio Naturalist. 
[Vol. Ill, No. 1 
the sternum, posteriorly with the metathoracic sternum and epis- 
ternum and dorsally with the metathoracic scutum. 
The coxa (8) of the mesothoracic leg appears globular on its 
surface, but is really as long as the prothoracic coxa, as will be 
seen by examining its internal surface. The coxal cavity is much 
smaller, however, and not circular. The coxa is dovetailed be- 
tween the trochanter and femur on the ventral surface and articu- 
lates over them on the dorsal surface. 
The trochanter (9) is fused to the posterior surface of the 
femur at its proximal end. The femur (10) is flattened dorso- 
ventrally and hollowed on its posterior surface from the distal 
end of the trochanter to the tibial joint. The mesothoracic tibia 
( 1 1 ) bears no spine at its proximal end. The articulation should 
be examined from the inner surface. On its dorsal surface it 
bears a dense row of bristles and at its articulation with the tarsus, 
four spines, two ventral and two lateral. The tarsus (12) re- 
sembles the prothoracic tarsus closely, having first and last seg- 
ments long and the intermediate ones short. 
By comparing the mesothoracic legs with the prothoracic 
these latter will be seen to be rotated through 90 degrees on their 
coxae so that posterior, anterior, dorsal and ventral are reversed. 
The metathoracic spiracle is situated on the hinder and upper 
border of the epimeron in the membrane connecting this sclerite 
with the wing articulations. It is usually tucked under the border 
of the epimeron. 
THE META-THORAX. 
The metathoracic sternum ( 1 ) forms the floor of this seg- 
ment between the second and third pairs of legs. Anteriorly it 
begins on the median line by a narow neck extending between the 
meso-coxae. The anterior boundary then curves around in front 
of the coxal cavity and comes into contact with the meso-sternum 
and ends antero-laterally in contact with the meso-thoracic epi- 
meron. Beginning with the hinder border of the coxal cavity and 
extending to the epimeron is a shallow groove marking off a nar- 
row strip from the anterior border to this sclerite. This is usually 
described as the mesothoracic epimeron, but is attached to the 
meta-sternum and cannot be separated from it. The lateral boun- 
daries of the meta-thoracic sternum are straight and begin at the 
mesothoracic epimeron and end at the metathoracic coxal cavities. 
The lateral border bears a shallow groove and the outer elevated 
wall of this groove is in contact with the metathoracic episternum. 
(2) throughout its whole length. Posteriorly the metasternum 
forms the anterior boundary of the metathoracic coxal cavity. 
The metathoracic episternum (2) is a long, narrow sclerite 
lying on the lateral border of the sternum from which it is sepa- 
