1912] Lacinia in Maxilla of Hymenoptera 233 
has changed somewhat the orientation of the parts. The galea 
is almost as long as the elongated stipes and is composed for 
the most part of a large lobe which is the homologue of the 
lateral lobe of the galea of the maxilla previously described. 
The homologue of the mesal lobe is much smaller and has 
changed its position somewhat. It is a small lobe placed on 
the surface of the larger, lateral lobe, nearer its lateral than its 
mesal margin. The mesal margin of the small, mesal lobe is 
marked by a row of long sete. All the sutures between the 
parts of the galea and the stipes are obsolete. There are several 
dark and light areas with oblique ridges where they probably 
fuse, but specimens prepared with caustic potash show no indi- 
cation of a suture in this region. The lacinia is a small but well 
marked lobe attached to the mesal margin of the proximal end 
of the stipes. Its position is clearly indicated in figure 6. The 
distal end of the lacinia is usually folded under the proximal 
end of the galea and more or less concealed. It shows distinctly 
on unmounted specimens studied in alcohol. 
A thread-waisted wasp, Sphex pennsylvanicus (Fig. 7), 
shows a somewhat different condition. In the maxilla of this 
insect the small, mesal lobe of the galea is wanting and the 
lateral lobe developed into a greatly elongated, blunt piece, 
which projects for some distance beyond the stipes and is almost 
as long as the maxillary palpus. There is a groove along the 
lateral margin of the galea that may mark the line of separation 
of the small, mesal lobe of the galea. Unfortunately it was not 
discovered until it was too late to remedy the defect, that the 
figure of this maxilla was turned in the oppsite direction from 
the others. The lacinia is located at the proximal end of the 
galea in this maxilla. It is a broadly rounded lobe. Its loca- 
tion and the development of the proximal end of the galea as 
an overhanging projection would suggest that the lacinia had 
been modified into a supporting piece. 
The greatest modification of the maxillz is found with the 
bees where they have been greatly elongated into plates for 
close appression against the labium for the formation of a tube. 
The maxilla of a bumble bee, Bombus terricola (Fig. 8), shows 
this condition well. The galea is a sword-shaped blade as long 
as the remainder of the maxilla. It is attached to the distal 
end of the stipes. The two are fused without any indication of 
asuture. There is an oblique ridge marking the edge of a deep 
