198 Wisconsin Academy of Sciences, Arts, and Letters, 
flexor to draw it inward toward the median line. The maxillary- 
palp is pubescent. Its flrst or basal segment is very short, and the 
third is like it; while the second and fourth are longer, each fully 
three times the length of either of the other two. The largest 
muscles of the palp (flg. 5, f.p.) extend to the inner edge of the 
stipes, crossing it ventral to those of the galea. Thus their con¬ 
traction would serve to draw the palp in toward the median line; 
a shorter muscle (fig. 5, ep.) attached near to those of the galea 
swings it out. On the stipes, just at the base of the galea, is a 
groove (fig. 5, fs.) through which the maxillary fork slides as if in 
a slot, and in which it is held in place by a band of tissue which 
arises from one wall of the slot and passes over the fork to attach 
on the other side. This slot has not been referred to before ex¬ 
cept as Hagen (15) described the fork as sliding “in the outer 
lobe as in a vagina ’ ’; yet this he did not figure. He spoke of the 
tip of the fork as sliding through a chitinous ring of the tip of the 
outer lobe, but this has not been seen in any of my preparations. 
The fork itself in Troctes is a straight rod ending distally in three 
sharp points of unequal length, the two outer longer than the 
inner. These ends are unlike the truncated tips of Psocus. At its 
base the fork is covered by strong muscles which in turn connect 
with a muscle (fig. 5, r.f.), not a ligament, as claimed by Burgess. 
This is probably the fork retractor, as it extends to the posterior 
wall of the head and would thus serve to draw the fork within the 
head by its contraction. The function of the forks is difficult to 
conceive, unless they could be used in so delicate a process as that 
of picking up mold spores and other small particles and drawing 
them into the mouth. With the close attachment which the maxil¬ 
lary fork bears through the slot to the stipes of the maxilla, it be¬ 
comes possible to consider it the homologue of an inner lobe, since 
there is no other sign of one in connection with the stipes. How¬ 
ever, even considering this, with the ultimate attachment of the 
fork to the posterior wall of the head, the old hypothesis of 
Burgess, that it is an independent organ, is still possible. In dis¬ 
section it is so easy to separate the fork from the maxilla that its 
real attachment through the slot is difficult to ascertain. Until 
observation is made of its origin in development this question will 
remain a matter of doubt. 
The labium is made up of a broad mentum (fig. 6, m.) which 
bears a pair of one-jointed labial palps (fig. 6, l.p.)—short, bluntly 
pointed, and covered with bristle-like hairs,—and two median, hair- 
