58 
Psyche 
[March-June 
fluent zone is short, frequently less than 20 per cent the length of 
the band. This section is the largest in Mystropomus , Metrius and 
Promecognathus where it is 30, 34, and 35 per cent respectively. 
The proximal section begins by curving posteriorly and goes hori- 
zontally across the tibial face and then curves dorsally and extends 
vertically up the tibia. Except in Hiletus (Figs. 10, 11), the vertical 
proximal section of the band is found on part of a flattened, medially 
expanded section of the tibia. The medial expansion is shaped like 
a triangle whose apex is at the level of the clip or guide setae and/or 
the most proximal point of the setal band, (Figs. 1, 22 MEx). The 
distal side of this triangle is curved in a gentle arc and bears band 
setae; while the proximal side, which is less flattened, forms the 
posterior border of the antennal channel. The medial expansion 
varies greatly in development and orientation. In some forms 
( Nomius, Figs. 12, 13) it is almost entirely vertical with only a 
slight anterior shift. The channel is parallel to the tibial long 
axis, as in Carabus (Fig. 2). In others ( Mystropomus , Metrius , 
Figs. 22-25, and Promecognathus ) the expanded region and the 
band are shifted distinctly anteriorly, but the channel extends far 
above the clip setae. As the tibia is expanded antero-medially, the 
clip setae and the proximal part of the band come closer to the level 
of the confluent zone. The anterior setal row consists of tightly 
packed short setae in single file and is probably used in antennal 
grooming (Figs. 1, 11, 13, 23, 25). The posterior row is formed 
from large, widely spaced setae (Fig. 21) or is absent (Fig. 23). 
In Grade C, the setal band is divided into a very long, straight, 
vertical distal region and a curvaceous proximal cleaning section. 
The anterior row is absent in many of these forms, in which case 
the non-grooming section of the band is called the distal zone (Fig. 
3D). The size of the distal section of the band readily characterizes 
most grade 'C configurations; it ranges from 33 to 69 per cent of 
the band length (15 to 34 per cent in grade B forms). This large 
distal increase in a non-cleaning part of the band results, of course, 
in a proximal shift of the cleaning elements (Figs. 14, 16, 26). 
The proximal antenna cleaning part of the band occurs on a 
vertical, highly curved region of the tibia. This cleaning arc, in 
posterior view, is distinct (Fig. 26 Ac). The cleaning arc has been 
formed by a complex set of modifications in tibial molding. The 
flattened medial expansion is larger than that of grade B configura- 
tions. The tibia along the distal region of the band is also produced 
medially. Antero-posterior compression of the entire tibia brings the 
ends of the cleaning arc closer together so that they lie in nearly 
