History and Habits of Pityogenes. 19 
of the workers were buried in the bark with only the end of 
the abdomen showing. One specimen was about half way 
in and several were wandering about on the bark. Each 
burrow started was marked for future identification by a 
cross scratched in the bark with a dissecting needle. All 
of the workers but one were males, although several females 
‘were burrowing between the bark and sapwood at the cut 
ends. The one female burrowing through the bark was 
working, however, in the same burrow studied two days 
before and known to have been started by a male. This 
would seem to indicate that while the female of this species 
is perfectly able to burrow the inner bark and sapwood she 
seldom or never burrows through the tougher outer pat of 
the bark, but will on occasion use burrows started by males 
and later abandoned. 
While observing this specimen with the binocular micro- 
scope a male happened along in his wanderings and after 
casually examining the female, chanced to find the cross 
mark scratched in the bark near her burrow. He imme- 
diately began working, biting out minute bits of bark and 
bracing his legs against the surface of the bark. In this 
way he worked along one cross line till he came to the june- 
ture of the two. There apparently finding a more suitable 
foothold, he elevated himself at an angle of about 45 degrees, 
taking the position shown in Fig. 6 and began work in 
earnest. Until the burrow has advanced far enough so that 
the front part of the prothorax is below the surface, the 
burrower seems to be working under considerable difficulty 
and it is apparent that suitable foothold is an absolute 
necessity. <A study of Fig. 6 will make clear how these 
difficulties are overcome. The fore legs are placed at the 
sides of the hole or slightly in front with the spines at the 
ends of the tibiae (Fig. 18) pressed against the bark, usually 
in rough places, while the tarsi extend forward and the 
claws grasp the bark. The ends of the tibiae of the middle 
and hind legs are pressed against the bark. In working, 
the middle and hind legs are straightened more or less with 
each effort of the mandibles mnie the fore legs, gripping 
