60 
Psyche 
[April 
Behind the ocelli and on the edge of the occiput is a transverse 
row of four macrochsetse. The inner, larger pair are the post- 
vertical bristles (pvt), and the smaller, outer ones, the inner 
vertical bristles (ivt). The outer verticals, present in some 
forms, are not represented in this species. The fronto-orbitals, 
which lie between the frontal bristles and the curve of the com- 
pound eyes, are also absent. 
On the fronto-clypeus, disposed along each facial ridge^ 
is a short row of facial bristles, the vibrissal row. The uppermost 
pair are the vibrissse (vib) which in T. pennipes do not assume 
from the front, which lies between the compound eyes, and be- 
tween these and the frontal suture. At the very top of the vertex 
their typical position immediately above the oral mragin, but 
are shifted upward to lie halfway between the oral margin and 
the tips of the antennae. The smaller bristles accompanying 
the vibrissae extend on either side in a single line along the oral 
margin to the region of the postgenae, where they mingle with 
the silvery-white beard which depends from this region. A 
single row of short macrochaetae extends around the edge of the 
occiput from the inner vertical bristles downward to the region 
of the postgenae. These are called the cilia of the posterior 
orbit (cpo). 
Appendages of the Head. 
Antennce. The antennae (ant) reach halfway between the 
base of the frontal suture and the oral margin. The first two 
segments are velvety-black in color, with a silvery sheen. The 
second segment bears a few macrochaetae. The third segment, 
which is much larger than the other two, is bean-shaped and 
varies from black to mouse-colored, with the base sometimes 
slightly tawny. This segment bears the arista (ar), a large 
bristle which is inserted on the outer edge about one third the 
distance from base to tip of the segment. The arista is prac- 
tically bare, having but a few very tiny hairs near its base. 
Proboscis. The proboscis (pb), usually folded well back in 
the oral cavity, is a very much modified structure, the parts of 
which it is very difficult to homologize with the mouth parts of 
