JAMES CHESTER BRADLEY 
2.57 
the outer surface of the middle tibae with a group of spines, and 
the posterior border of the hind til)iae with a row of a few spines, 
or any or all of these may be wanting. The claws are simple and 
slender. 
The length of the first abdominal segment, whether it is con- 
stricted from or dorsally sessile with the second, whether it has an 
anterior narrow portion or neck, or whether it is enlarged directlj" 
from the base, are all matters of great importance in the differ- 
entiation of species. Sometimes it forms a long petiole, varying 
from slightly to strongly nodose, while again it may be short 
and not at all petioliform. Its sides are either coarsely punc- 
tured, or simply roughened by the insertion of numerous upright 
hairs. In giving measurements of this segment I have taken its 
length along the ridge or carina at its side, and its greatest dorso- 
ventral thickness as seen from a strictly lateral view. The second 
ventral segment is usually more or less evenly convex, but in one 
species is truncate basally, with the truncate portion separated 
by an undulating, transverse carina. In a few species there is a 
short, median, 'basal, longitudinal keel on this segment. The 
setae of the second to sixth abdominal segments inclusive are 
almost invariably grouped into a sinuous or V-shaped closely-set 
row on each segment, as a rule about two-thirds of the way from 
the base to the apex, arising from well marked small punctures, 
while there are only very few scattered over the rest of the 
surface. In one or two species, as notably stygia, these rows 
become indistinct, or at places altogether lost in a mass of seti- 
gerous punctures scattered over the abdomen. The pygidium is 
narrow and notched, truncate or obtuse at tip, with or without 
lateral margins, sometimes with a raised, median, longitudinal, 
impunctate, polished strip, and with a varying number of coarse, 
setigerous, lateral punctures. 
I am not certain of the homologies of some of the parts of the 
geiiital’a nnd use <^^he terminology only tentatively, endeavoring 
to make it correspond with that used by Dr. Franklin for the 
Bombidae.® The uncus is an unpaired median organ, varying 
greatly in shape in the different species, sometimes with a ^'- 
^Franklin, Ilenrj- J. The Bombitlae of the New World. Transactions of the 
American Entomological Society. 1912. 3S: 177-4.SG. 1913. 39: 73-200. 
22 1 ) 1 . 
TR.\NS. AM. ENT. SOC., XLIII. 
